-High in the cliffs near Luxor lies a mysterious mass grave.

-Filled with bodies. Wow.

What a nice foot.

-Who were these people?

-Generally, you don't get mass graves in Ancient Egypt.

It's a very rare thing.

-And how did they end up here?

-Something like a mace struck him on the side of the head.

These people have died bloody fearsome deaths.

[ Suspenseful music plays ] -Now, archaeologists and scientists from around the world scour through the sands in search of clues to solve this mystery.

-It's great. For me, it's great because it's the first time for me to get inside this pyramid.

Really exciting.

-From the Great Pyramids at Giza [ Wind whipping ] to the glaciers of Mount Kilimanjaro... -The fact that the pyramid was robbed means the government was losing control.

-...a series of political crises... -Setting fire to a temple, a sacred place belonging to the king shows a direct attack against Pharaoh.

-...and environmental catastrophes... -This represents a major drought.

-...plunged Egypt and its people into anarchy... -If anything goes wrong with the Nile, then it would be famine and chaos.

-...and triggered a dramatic civil war which would last almost 150 years.

Were these mysterious bodies casualties of this war?

If so, who were they fighting for?

'Egypt's Darkest Hour.'

[ Suspenseful chords striking ] ♪♪ [ Suspenseful music plays ] ♪♪ ♪♪ -The desert cliffs of Luxor, in Southern Egypt... -[laughing] -...are home to an exceptional tomb.

♪♪ Dating back more than 4,000 years, long before Cleopatra, before Tutankhamun and Ramses, it's a rare mass grave.

First discovered in 1923, it was sealed off and very few people have entered since.

But, today, this unique grave is being opened for archaeologist Salima Ikram.

-It's amazing to be able to go into this tomb.

It's a huge privilege.

No one's been allowed to go in for a long time and I've always wanted to go in since I was a baby Egyptologist, so this is a real treat.

♪♪ -Little is known about this burial site and Salima wants to find out who is inside, and why.

-Door's open, but we have to wait for the air to clear a bit.

There's still a lot of dust and there's still a lot of dead stuff.

♪♪ [ Suspenseful chord strikes ] ♪♪ -After half an hour, it's safe for Salima to enter.

-Light saber.

Finally, we can really go in and see this tomb for the first time.

♪♪ Wow!

-Carved out of rock by hand, the tomb consists of 200 feet of branching tunnels that reach back -It's like a labyrinth in here.

It keeps on going.

There are rooms and twists and turns and tunnels.

It's fantastic!

♪♪ And it's with bodies.

Wow!

And lots of bandages.

♪♪ [ Grunts ] Here's a shoulder.

You can see the scapula, a little bit of scapula here, and here's a humerus.

So, so, it'd sorta be like this.

You can see whoever it was was taller than I am, quite robust, probably male.

♪♪ Here, you can see all the folds of flesh.

♪♪ And over here, we have someone's leg.

♪♪ All these bandages would've been wrapped around the bodies, protecting them, allegedly, for eternity.

-The tunnels contain the remains of least 60 people.

♪♪ -Just keeps on going.

♪♪ Oh!

What a nice foot.

Left foot with his big toe intact.

Small toes have fallen off.

Quite a large foot.

It's probably male.

-To add to the mystery, the bodies seem to be male.

here's its mate.

They're all intact.

♪♪ -This grave is extremely unusual for Ancient Egypt.

-There are numbers of bodies in here and, generally, you don't get mass graves in Ancient Egypt.

-Normally, Egyptians were buried alone, or with their family.

-But it's only when you have plagues or battles, where you might have a mass grave, like this one.

It's a very rare thing.

-Can science provide the identities of these bodies?

♪♪ French archaeologist Audran Labrousse is an expert on this period of Egyptian history, known as the Old Kingdom.

To find out who these people were, he begins with an ancient text.

Written by the poet Ipuwer, it's thought to describe Egypt at the time leading up to the mass burial.

And Ipuwer's poem suggests something terrible happened to Egyptian civilization.

-See now, the land is deprived of kingship.

The king has been robbed, deposed by beggars.

Every town says, 'Let's expel our rulers.'

The people of the land weep because their enemies have entered the temple and burned the images.

Upper Egypt becomes a wasteland.

♪♪ -According to the text, Egypt was in total chaos, which could help explain the dead in the mass grave.

Some historians doubt the veracity of Ipuwer's text, rejecting it as exaggeration or pure fiction.

However, Audran thinks there may be some truth to what the ancient poet wrote.

♪♪ Together with his colleague Philippe Collombert, he's come to Saqqara, where the pharaohs were buried in their pyramids, just south of Cairo.

♪♪ Between them, Audran and Philippe have spent more than 50 years studying the pyramids.

Today, they've been given permission to open a very special pyramid they believe contains evidence explaining why the bodies were interred in the mass grave.

-We're going now to the pyramid, the last pyramid, of the Old Kingdom and we're quite excited because we'd like to open it and to see exactly what is inside.

♪♪ -It will be very interesting to get inside the pyramid.

It has been closed for And we have the luck, the chance, the privilege, to get to the sarcophagus and make a study of the monument.

♪♪ -It's just over there.

You can see it in the background.

♪♪ And here we are.

-Yes, the pyramid.

♪♪ -So here it is and it belongs to the Pharaoh Pepi II.

-The story of the bones in the tomb starts with the end of Pepi's reign.

Who Pepi II?

Pepi II came to the throne around 4,300 years ago, at the age of just six, 250 years after the Great Pyramids and the Sphinx were built.

By this time, the pharaohs had ruled Egypt for about 700 years.

This great civilization extended from the Mediterranean to Aswan.

As pharaoh, Pepi was believed to be the son of a god and he ruled for at least 60, some say even 90, years, the longest reign in Egyptian history.

♪♪ His long reign gave him plenty of time to build a magnificent pyramid.

Its grandeur demonstrates the extent of his wealth and power.

-The main masonry of the pyramid is made of small stones cemented with mud, as to form a huge staircase toward the sky.

Against these small stones, you had a thickness of about 5 meters of huge limestones blocks.

-And, finally, on top of this, the outer layer of the pyramid, made of the finest, whitest, limestone in all of Egypt.

-This casing covered the pyramid on 50 meters high and a golden top was added.

It must have been a very impressive monument.

♪♪ -The funerary complex had a temple dedicated to Pepi and included small, satellite pyramids for his spirit and three medium-sized pyramids where his wives were entombed.

But this magnificent pyramid was to be the last of this golden era.

After Pepi's death, around 4,200 years ago, traces of the Old Kingdom disappear into the sand.

Perhaps the turmoil written about in Ipuwer's ancient poem was real.

♪♪ [ Conversing in Arabic ] Audran and Philippe are entering the pyramid to find out what was happening in Egypt at this time.

-[ Speaking in Arabic ] -Audran mudir!

[ Conversing in Arabic ] -But the pyramid isn't giving up its secrets easily.

-So we're in it now.

We're approaching the entrance of the Pharaoh Pepi II.

[ Suspenseful chord strikes ] ♪♪ -It's taken the workers more than four to dig down through nearly 15 feet of sand.

♪♪ -We are nearly coming to the end of the work.

We still have some bit of sand to take out of the entrance and we will be in it.

-Finally, the sealed entrance to the pyramid is revealed.

-So, now, we're ready to start.

We're gonna break the cement.

♪♪ -The pyramid was last studied in the 1930s and hardly anyone has had the privilege of entering it since.

♪♪ It is an amazing opportunity for Audran and Philippe.

♪♪ -It's great. For me, it's great because it's the first time for me to get inside this pyramid.

Really exciting.

♪♪ ♪♪ -The passageway descends steeply and then levels off, continuing for about 85 feet directly into the heart of the pyramid.

-Well, now, we're in the passage and just leading to the burial chamber.

-At the very center, they reach the antechamber, which then leads to the burial chamber, where the pharaoh was laid to rest.

-[gasp] Ooh la la la.

Pssh!

This is really amazing, amazing.

♪♪ ♪♪ ♪♪ I'm really amazed by the state of preservation of this pyramid, with all these marvelous texts all around.

It look like the painter just left yesterday and we're just coming afterwards.

You see the green color and the white surface; even the line here, the black line, are still present.

♪♪ And, here, we have the sarcophagus with the inscription with the name of Pepi II.

This sarcophagus is the master piece of the Old Kingdom.

It's really huge and magnificent, really nicely done.

-This massive stone sarcophagus weighs 11 tons.

-The sarcophagus is made of a black stone but you have to imagine that it was covered of gold.

The inscription was in gold and inside it was a thick, gold leaf.

And you have also to imagine in front of the sarcophagus, filling the room, all the golden furniture, the vases, everything that the king needed in his afterlife.

-And the walls of the chamber are covered in hieroglyphs of ancient Egyptian religious texts.

♪♪ -All these texts are ritual texts for the rebirth of the king in the afterlife.

-For Audran and Philippe, the interior of the pyramid reveals the state of the country during Pepi's reign and the events leading to the mass grave.

-When you see the sarcophagus, with all these marvelous texts all around, that shows that, at the beginning of the reign of Pepi II, the state is still really powerful.

-Egypt is triumphant.

-But Philippe and Audran have spotted signs that things changed.

For one, the pyramid was looted.

-As you can see, the sarcophagus has been opened up and all that was inside has been robbed and taken out.

-Including Pepi II's mummy, which has never been found.

-When the robbers arrived, they pushed the lid of the sarcophagus, opened the coffin, took the royal mummy, throw it away.

And, of course, all this gold, it was fabulous.

They took everything out and the archaeologists found absolutely nothing in this room, unfortunately.

[ Sinister music plays ] -Back at the entrance tunnel, Audran is studying evidence which shows that the pyramid must've been robbed shortly after Pepi's death.

After Pepi was buried, the original passage was sealed with massive stone blocks, but the looters found a way around them.

-Here, we see the evidence of the pillaging of the pyramid.

The looters break the façade.

-They then dug through the limestone brickwork, until they bypassed the stone blocks.

-The looters cut the lintels and went into the descending passage.

-Farther on, they dug a second tunnel above the main passage.

It's now been filled, but Audran has found traces of it.

-The looters arrived to this lintel.

They break it.

You can see some traces above.

-Why did they dig this second tunnel?

-The passage was blocked by three unpenetrable granite portcullis.

-Today, they are raised, but, at the time, these massive, granite blocks barred the way.

The looters had to dig through the softer limestone to get around them.

[ Suspenseful music plays ] ♪♪ -They came down here, after the third portcullis, and then, their passage was clear to the funerary chamber.

-The efficiency of the looters' route belies they broke in.

-It means that the looters knew perfectly the plans of the pyramid.

They had in their crew somebody who had built the monument and it shows that this must have happened shortly after the death of Pepi II.

[ Sinister music plays ] -Looting the pyramid so soon after Pepi's death is a sure sign the country was in turmoil.

-When they took out the mummy of Pepi II, first, of all, it was a very big sacrilege.

-Ancient Egyptians believed they needed their body to live again in the afterlife, which is why mummification was so important to them.

-Destroying his body means that Pepi II will never be able to live again.

That's real death for the pharaoh.

-Protecting the pharaoh's mummy was a critical task.

-The pyramid was closed after the burial of the king and it was guarded by a lot of people around the pyramid, so nobody could approach.

The fact that the pyramid was robbed means that the state, the government, was not controlling anything here.

[ Suspenseful music climbs ] [ Suspenseful chord strikes ] -And that's not all.

Nearby, next to Pepi's father's pyramid, Audran has found evidence that the country was in trouble shortly after Pepi II died.

-We are here in one of the storerooms of the temple of Pepi I.

And you can see that the stones are black, they are burned, and it shows a very violent and destructive fire.

The fire, of course, was deliberate.

-Crucially, Audran's team was able to date this fire.

-We were able to date the fire by radiocarbon and it dates from the end of the Old Kingdom.

[ Flames crackling ] -The date of the fire supports Audran's theory: that Pepi II's pyramid was pillaged not long after his death.

-Setting fire to a temple, a sacred place, belonging to the king, shows a direct attack against power, against royalty, against Pharaoh.

-Shortly after he died, law and order broke down to such an extent, his pyramid, and those of his family, were robbed and desecrated.

[ Flames crackling ] More evidence to suggest Ipuwer may have been telling the truth.

-The king has been robbed.

The people of the land weep because their enemies have entered the temple and burned the images.

♪♪ -What happened?

How and why did the pharaohs lose control and how did this lead to the dead in the mass grave?

All over Egypt, archaeologists are finding signs of the growing political problems that were festering before Pepi II's death.

♪♪ As Pepi's reign continued and he grew older, he began ceding more and more power to his provincial governors.

♪♪ 500 miles south of Saqqara, on the banks of the Nile, lies the necropolis of Qubbet el-Hawa.

It's here that the governors of Southern Egypt are buried and, with them, striking evidence of their growing influence.

Archaeologist Martin Bommas -has been digging here for three years.

Comparing the tombs of governors from the start and end of Pepi's reign, he points out signs that their authority was increasing over time.

[ Suspenseful chord strikes ] -Here we are, right at the entrance into the Tomb of Harkhuf, the governor of Upper Egypt, at roughly the time when Pepi II was a child and, as part of his role, he went to Nubia four times, to bring back exotic goods, like leopard skin, elephant tusks, and so on.

♪♪ [ Suspenseful chord strikes ] ♪♪ He was sent out by the king, obviously.

The king financed all these expeditions.

What is really interesting is that, although Harkhuf was one of the most important men in the region, really running the business here, he still had to ask Pepi II for permission to build his tomb.

-At the start of his reign, Pepi II was very much in control of the country.

-When we look into the political situation of Egypt at this point in time, we see that the king is still very strong.

-But during the course of his long reign, things changed and those changes are reflected in the style and construction of the governors' tombs.

Because, as grand as this grave is, it's compared to the tombs of two governors from the latter part of Pepi's life, which are at the far end of the necropolis.

The first one belonged to a governor of Elephantine.

-Look at the size of this tomb and look at the columns, how high they are.

That gives us an idea about the importance of the governor of Elephantine.

Eighteen columns here.

It's almost like a forest of columns.

-The majesty of this tomb illustrates Pepi II's weakened authority, while the regional governors were becoming increasingly important.

And the adjoining tomb, belonging to his son, is even more elaborate.

-Now, look at this lavish painting here, that shows Sabni on a boat, on a river, but not during this life.

It's the next life. It's the beyond.

-The painting, together with the sheer size of the tomb, tells a story of wealth and influence.

-If we relate what we see here to the beginning of the reign of Pepi II, like what we've seen in the tomb of Harkhuf, this clearly points out that, by the end of Pepi II's reign, when he was an old man, local governors had more power.

♪♪ -And this situation was replicated across Egypt.

Pepi II gradually relinquished more power and control to the local governors.

-Suddenly, local governors had too much power, compared to the power that was decreasing in the capital.

-A political crisis was brewing.

Then, at the age of 94, Pepi II died, and the fragile political situation finally unraveled and so began a series of events that led to the remains in the mass grave.

[ Flames crackling ] ♪♪ There are hardly any traces of Pepi II's successors.

Audran has been searching for these kings for years.

One of his few sources of information provides insight into the leaders who followed Pepi.

-We are lucky enough to have the list of Abydos.

It is a list engraved on a temple, giving the names of all the kings of Ancient Egypt.

And we have the names of five sons of Pepi II.

-None of Pepi II's five sons reigned for very long.

-The first successor of Pepi II was called Merenre II and we know, according to the Greek historian Herodotus, he was murdered after a very short reign of two years.

♪♪ -And his brothers didn't last much longer.

-We know that Pepi II has a very long reign, between 60 and 90 years.

So, his sons were very old when they arrived at the throne.

Perhaps they just die because they were too old.

-After his five sons, the crisis worsened and the Abydos list shows 13 more kings in quick succession.

That's 18 kings in roughly 50 years.

The Old Kingdom was clearly in freefall.

♪♪ To this day, archaeologists have not been able to find any physical evidence related to these kings.

With the exception of one.

It might not look like it, but this uninspiring pile of rubble is actually the remains of a pyramid.

It belonged to Qakare Ibi, the fifteenth king after Pepi II.

♪♪ And it's tiny: less than half the height of Pepi's pyramid.

♪♪ The small size of Ibi's pyramid illustrates how weak the royal authority had become following Pepi II's reign.

And, after Ibi's, it seems, no pyramids were built for about 200 years.

♪♪ [ Horn toots ] [ Poignant tune sweeps ] What was happening in the rest of the country, while the power of the pharaoh was waning?

400 miles to the south lies El Mo'alla.

♪♪ Once again, the style of a tomb signifies how the local governors responded to this succession of ephemeral kings.

Archaeologist Antonio Morales explains.

-This is Ankhtifi, the owner of this tomb, the local ruler of Hefat, the third province in Upper Egypt.

-Ankhtifi governed in the tumultuous years between Pepi II's death and the creation of the mass grave.

-These inscriptions tell us a lot about social disruption, civil war, conflict, lack of order or control by the central administration.

There was a big gap of royal control of the country.

-Most tomb walls are covered with references to the ruling king, but not here.

-This is the only place in the whole tomb where Ankhtifi mentioned the name of a king.

The rest of the tomb does not have a single mention to any king, which probably means that, with the passing of time, the central government lost control of the country and Ankhtifi felt that he was the single power in his province.

-And, on his tomb walls, he's portrayed himself as king and ruler of his province.

-He used kinds of phraseology, expressions, and even iconography that usually was used during the Old Kingdom, only by the kings.

This section of the inscription says 'I am taking care of the orphan.

I am giving a boat to the one who cannot cross the Nile.'

By doing this, he was somehow comparing himself to the king, since these kinds of expressions referred to the capacity of the king to provide for his people and his country.

-It seems that, after Pepi's death, rather than submitting to a rapid succession of weak pharaohs, the local governors, like Ankhtifi, decided to rule for themselves.

The regional governors began jockeying for power and the inevitable consequence was civil war.

-Some of the inscriptions in the tomb of Ankhtifi talk a lot about civil war.

Here, for example, we have the verb 'to attack, to fight,' and includes the determinative of man with a stick and he's expressing how he was going to attack the Theban province.

♪♪ So, we have a situation of social disruption, civil war, conflict.

♪♪ [ Tranquil tune plays ] -All of this supports what the ancient poet Ipuwer's work described.

-The land is deprived of kingship.

-Pepi II's heirs lost their grip on the country.

Egypt split apart and plunged into chaos and war.

[ Suspenseful music plays ] Salima thinks it's possible that the bodies found in the mass grave near Luxor perished in the civil war.

-I've got some photos of men who were inside the tomb and a lot of them had trauma.

You can see, over here, there's a hole here and he's probably hit by, you know, a rock from a slingshot.

This one's even worse, 'cause you can really see that there've been attacks here, on both sides.

So, this is quite possibly something like a mace struck him on the side of the head and blew it out and killed him rather viciously.

So, this was not someone who died in bed.

This was someone who died in battle.

And some of them actually had arrows going through their bodies.

So, here's the arrow and so he was pierced through and he would've been lying, bleeding, on the battlefield, probably waiting to be rescued or slowly dying and having birds pecking at him.

These people have died bloody fearsome deaths.

[ ] -In addition to the brutal manner of their deaths, there are other clues to their identities.

-They were buried with their bows and arrows.

So, we have those.

And this is really the clincher.

♪♪ This one's got a wrist guard that goes all the way up and that's what archers wore to protect themselves from the bow's recoil.

So, these people were archers themselves.

So, all the evidence points to the fact that these were soldiers who died in battle.

♪♪ -But who were these soldiers fighting for, and why?

♪♪ ♪♪ The hieroglyphs on Ankhtifi's tomb reveal a catastrophic event that might explain.

-Here, it says the whole southern country was dying of hunger, so that every man was eating his own children.

♪♪ Also, in this section of the inscription, it says, the whole country has become like a starving locust.

That is a clear way for Ancient Egyptians to express that there was a dramatic famine in this section of the country.

♪♪ -Already politically weakened by the rise of the governors and the succession crisis after Pepi's death, a famine could have been the final blow that brought down the Old Kingdom.

♪♪ There is mounting evidence from all over the world that planetary forces could have caused such a famine.

♪♪ Scientists are discovering that, long before Pepi, Egypt wasn't the desert it is today.

♪♪ Back in Saqqara, Audran has found something revealing on the pathway leading to another pyramid, that of Unas, Pepi II's great-great-grandfather.

-The wall of the causeway were covered with reliefs.

Among them, one is specially interesting.

What do we see?

We see various animals.

We see antelopes, oryx, gazelle, and among them there are small bushes and we see, for instance, here a very small gazelle, more or less sleeping among bushes.

In fact, it's the representation of a savanna.

-Audran believes these carvings show that Egypt once had a very different climate than it does today.

-It means that, at the time of the Old Kingdom, the pyramids were not surrounded by a desert.

They were surrounded by a savanna, very close to what we found now in Kenya.

The necropolis was not a place of death.

It was a place of life.

-But are these decorations enough to prove these animals lived nearby and that the climate was so different?

Or are these carvings simply fanciful illustrations of animals seen while on expedition?

There should be scientific evidence, if Egypt's environment was radically different in the past.

That evidence comes from a very unlikely source: crocodiles.

♪♪ To find out more, Salima has come here, to Kom Ombo Temple, where Ancient Egyptians worshipped the god Sobek, who had the head of a crocodile.

She's here to examine an altogether different type of mummy.

-One of the most important gods in Ancient Egypt was the crocodile god Sobek and, as a result, priests actually raised crocodiles, so you have places where you have hatcheries for the eggs and then they also would have nurseries for the baby crocodiles and sometimes these were killed deliberately, with their heads being bashed in so that they could then be mummified and be given to Sobek as an offering.

♪♪ The ones that were recognized by the priests as having the divine spirit in them were allowed to grow to their full length, 5, 6 meters, and, during the lifetime of that animal, he would be fed and revered and looked after and spoilt rotten, in general.

Some of them, according to the Greek writers, had earrings of gold and bracelets made of gold put on them, so someone had to be very brave to go and do this to the god.

♪♪ -And, after their death, the crocodiles were carefully mummified.

♪♪ Surprisingly, these sacred crocs can provide details on Ancient Egypt's climate.

In 2003, zoologists studied crocodiles living in isolated pools in Mauretania and Chad.

These West African crocs are smaller and more docile than the more familiar Nile crocodiles found in East Africa today.

And DNA analysis has revealed these smaller animals are, in fact, a separate species, called The DNA analysis also revealed they're the exact same species as the sacred Ancient Egyptian crocodiles.

-Recently, we've been doing DNA on mummified crocodiles and the results have been truly spectacular because we did a and it turned out to be which is a desert crocodile.

In a way, it makes sense that these nicer, kinder, gentler ones were allowed to grow and sort of co-habit with humans and be the benign version of the crocodile god.

-How did the pharaohs' sacred crocodiles end up on the other side of the African continent and what does that mean for Ancient Egypt's climate?

-So we know that we have mummified in Egypt and we know that we have living quite a few of them, in fact, in the deserts of Mauritania, as well as in Chad.

So here we've got these populations that are quite far apart, but they're the same animal.

So what was going on here?

We started to look for fossils, to see if we could find these different populations of crocodiles together.

And, throughout the Sahara, we've, in fact, found lots of fossils of crocodiles, in Libya, Niger, in Mali, throughout Algeria, and also in Morocco.

So that means that, in ancient times, all of the space must've been connected by a series of waterways, for the crocodiles to move to and fro, and it wasn't always the desert that it is today.

♪♪ -5,000 years ago, the Sahara Desert was actually a savanna, crisscrossed by a network of interconnected waterways, which allowed crocodiles to move freely throughout North Africa.

The carvings on Unas's causeway reflected reality.

[ Birds chirping ] When the pyramids were built, they were [ Insects chirping ] But, when did Egypt dry out and become a desert and could in the demise of the Old Kingdom and led to the mass grave?

♪♪ Elephantine, in the middle of the Nile, between Qubbet el-Hawa and Aswan, can shed some light.

♪♪ The ruins here show what was happening to Egypt's climate.

♪♪ Archaeologist Miroslav Barta describes the changes.

♪♪ -This is a fortress dating back to 3,000 BC.

At the time, the island of Elephantine consisted of two separated islands: the eastern one and then the western island.

♪♪ The fortress is located in here, on the eastern island.

-The fortress was built on the highest ground, 315 feet above sea level.

-The reason was that the Nile flood at the beginning of the Old Kingdom was very high.

♪♪ -But the buildings surrounding the fortress show that the level of the Nile began to fall.

And, as the water level fell, the city expanded over the rest of the eastern island, which had been partially submerged.

And there are even ruins from the lowest part of the island, where the Nile once flowed, that date from Pepi II.

♪♪ -Now, we stand in the middle of the original depression that was separating the eastern and western island of Elephantine.

And, as we can see here, the ancient Egyptians were able to use up the original depression to construct their houses over it.

-After Pepi II's death, the level of the Nile had dropped so significantly that the two islands merged into one and the city expanded onto what had previously been the marshes in between.

Here is evidence that Egypt's climate was gradually changing and becoming drier during the Old Kingdom.

[ Triumphant music plays ] But things would get worse, much worse.

[ Foreboding music plays ] [ Wind blowing ] The key to understanding the collapse of the Old Kingdom, the reasons for the mass grave, lies almost 2,000 miles away, in the glaciers of Mount Kilimanjaro.

In 2000, an expedition of American glaciologists, led by Professor Lonnie Thompson, discovered proof of a global climate catastrophe.

♪♪ An ice cap is built of layers and layers of snow gradually piling up that are then compressed into ice.

By extracting cores from the ice, Lonnie is able to look back in time.

The ice captures a record of what was in the air at the time it was laid down.

Studying this ice back in the lab, Lonnie can reconstruct the past climate.

These precious cores are preserved in Lonnie's freezer at Ohio State University.

-We have over 7,000 meters of ice cores collected from around the world.

We have, on this particular rack, those cores which we recovered from Kilimanjaro in 2000.

It dates back 11,700 years and, in that record, about the depth of 33 meters, we would find the time that corresponds to the Old Kingdom in Egypt, so we'll take this out and examine it on the light table.

-This piece of ice holds a unique record of the climate around the time the Old Kingdom fell apart.

-This is what's left after all the measurements have been made on the core, so.

And this record starts about 5,000 years before present, so we're coming forward in time and you see this very distinct band.

♪♪ And it was really amazing, in the field, when this thing showed up, yeah.

There's a lot of excitement because you know you have something.

It's gonna take you a while to figure out.

No, it's very exciting.

-This ominous, dark layer is the result of the dramatic climate change that led to the collapse of the Old Kingdom.

-This black line that you see here in the core is a layer of dust, windblown dust, that accumulated on the ice field.

This is the largest dust event we've found in an ice core, so it's very, very highly concentrated.

It would suggest that there was a massive drought throughout this region.

-And Lonnie has found more physical signs of this drought, on the other side of the world.

-In the same time period, we have found a similar layer in the Huascarán ice cores in the Andes, in Peru.

We also see it over in the Himalayas, which suggests that there was a major drought throughout the tropics.

♪♪ -Crucially, he was able to date this drought.

[ Music intensifies ] -Based on our Kilimanjaro timescale, we estimate the event occurs around 4,200 years ago, the time of the collapse of the Old Kingdom.

♪♪ -Could this massive global drought have been what brought the Old Kingdom to its knees and led to the death of the soldiers in the mass grave?

[ Suspenseful music climbs ] [ Suspenseful chords striking ] [ Foreboding music plays ] Over the course of the Old Kingdom, Egypt was gradually turning from savannah into desert.

Agriculture was entirely dependent on the annual flooding of the Nile.

Each summer, the rains falling on the highlands of Ethiopia flow into the Nile, causing it to overflow its banks, flooding the fields and depositing rich soil which fertilizes the crops.

[ Suspenseful music plays ] If Lonnie is right, this climate spike would have had a disastrous impact on the Nile floods the people of the Old Kingdom.

[ Wind blowing ] Back in Egypt, geologist- turned-archaeologist Professor Fekri Hassan has been looking for proof that this global calamity did, indeed, hit the land of the pharaohs.

-There were indications that there are problems in other parts of the world at that time, caused by climate change.

It was tempting to think that this might be the case in Egypt as well.

-But, in Egypt, there is no ice.

He's had to find another way of seeing into the past: mud.

He takes cores from the bottom of Lake Qarun, just south of Cairo.

The lake is fed by the Nile, which deposits layers of sediment on the bottom, and, just like ice, these layers hold a record of the past climate.

Back in the lab in Cairo, Fekri has analyzed the cores.

-These were the cores we got.

It consisted of a sequence from the bottom of the lake that spans 10,000 years.

These are the oldest ones, that were before the rise of civilization, where the lake was quite deep and, as we move to this way, this part it the Old Kingdom.

This is the whole history of the Nile floodplain over the last 10,000 years.

It's never been available before.

-The core reveals that, during the Old Kingdom, the lake was much larger and deeper than today... ♪♪ ...its depth fluctuating around 200 feet.

-This part of the core here is the part that represents the Old Kingdom.

What is amazing in this part is this break, where we had the presence of a thick layer of gypsum, the whitish material.

This is a mineral, which forms under shallow water conditions and evaporative conditions.

Mixed with the gypsum, we have the deposits of the iron oxide, the reddish material.

Iron oxide usually form under very shallow water conditions, where oxygen is present, either very, very shallow water or almost no water.

That would mean that the lake was almost dry; if not bone-dry, just extremely shallow pools.

[ Ethereal vocals join ] -The layer of gypsum and iron ore shows that this deep, freshwater lake dried up, leaving behind just a few ephemeral pools of water.

-You know, maybe 60, 70 meters of water disappeared.

♪♪ From the different radio carbon age determinations of the core, we were able to determine that this layer here represents time around 4,200 years ago, which correlates to the end of the Old Kingdom.

♪♪ -Fekri's discovery confirms that the global drought seen in the ice cores also hit Egypt hard, just at the time the Old Kingdom collapsed.

-We were able to find the smoking gun.

This is the hard evidence for this event, this catastrophic event.

The thickness of this layer and the fact that the very deep lake had to dry up, it would indicate that we are dealing with no less than 20 years of reduced Nile floods.

-This disastrous drought was the knockout punch which pushed Egypt into chaos.

-I think climate change leading to a reduction of Nile floods is the cause of the collapse of the Old Kingdom.

Egypt depends on the Nile.

If anything goes wrong with the Nile, then it would be famine and chaos.

If the Nile is low for 20 years or even more, it means that agriculture production would stop.

-Ankhtifi, the local governor, was right: the whole of Egypt would've been like a starving locust.

-That means that the king does not have enough revenues, not even for his own household, not to mention for the viziers and the managers and people engaged in the governments, so, the whole civilization comes to a stop.

[ Suspenseful music climbs ] It's a great lesson about how abrupt climate change can be and how civilizations, no matter how mighty they are, can really suffer from events like that.

[ Outro plays ] -This terrible climate crisis, combined with the underlying political problems, created the perfect storm, which destroyed the Old Kingdom and ultimately set the stage for the mass grave.

In the face of famine and economic crisis, Pepi II's politically weak successors lost control of the country.

Egypt fractured into city-states.

But the turmoil and violence would last far longer than the drought itself.

[ ] Even as the 20-year drought ended and the Nile level rose, Egypt remained divided and vulnerable.

As prosperity gradually returned, it wasn't long before the regional governors, like Ankhtifi, developed ambitions to conquer the whole country.

The consequence was war for 130 years.

[ ] The soldiers in the mass grave likely died, not in the initial chaos caused by the famine, [ Poignant tune plays ] but right at the end of the protracted civil war that followed.

Roughly 40 years after the drought ended, the rulers of Thebes, modern-day Luxor, took control of the South and the location of the mass grave near Luxor suggests the soldiers were Thebans.

Meanwhile, another family of local rulers, from a town called Heracleopolis, had taken control of the North. [ Sinister music plays ] Egypt was split in two and both sides wanted control of the entire country.

In 2040 BC, the Thebans captured most of the North and they reached Heracleopolis itself.

They were led by a king named Mentuhotep II.

He was a great general.

His name even means 'Montu the god of war is satisfied,' and he finally conquered Heracleopolis, [ ] in a bloody siege.

[ Suspenseful music climbs ] [ ] [ Wind whistles ] Salima believes it's possible that these soldiers, now more than 4,000 years old, took part in this final battle.

-Amongst these bodies, there was a lot of linen and some of the linen had marks on it.

And these are actually associated with the temple of Mentuhotep II.

This, together with the fact that the temple is right there, underneath his tomb, means that the soldiers were fighting for Mentuhotep II.

[ Sinister music plays ] -And that's not all.

Close analysis of the injuries provides more details about what caused them.

-Looking at these arrows that went into the necks of these soldiers, you can see that the trajectory is from above and it's the same thing with all of these head wounds.

It's like someone was hitting them from above.

So, clearly, it would seem that these soldiers were up against an enemy that was higher than they were, as if they were in a fortress, as if there were some sort of siege situation, and that these soldiers of Mentuhotep were attacking some kind of fort and people were hitting them from above, raining down arrows, throwing rocks.

And, maybe, when they came too close, hitting them hard with clubs and maces.

[ Suspenseful chords strike ] -It would seem these soldiers were fighting for Mentuhotep in the deciding battle of the civil war.

-All of this put together makes us think that these soldiers were fighting at the siege of Heracleopolis.

-After the battle was won, Mentuhotep II declared himself king of the entire country, reunifying Egypt at last, and he is believed to have had the soldiers buried above his own mortuary temple as a sign of honor.

-It's a huge honor for anyone to be buried that close to the king, so, clearly, he valued them and he, himself, must have paid for the funeral, with all of these temple linens being used.

So, obviously, he valued their work and their loyalty and their bravery and kept them near him so that they would be united for eternity.

[ Suspenseful chords striking ] [ Suspenseful music climbs, chords striking ]