A human skull was found in April 2013 after heavy rains destroyed a section of the Great Wall of Kabul. Tests have determined that the skull is about 460 years old. (Courtesy of Mohammad Younas Nawandish)

Nearly everyone here knows the legend. Kabul residents recite it at random moments, whenever they catch sight of Sher Darwaza Mountain in the distance. Look closely, they tell visitors, and you will see an ancient wall running along the mountain’s edge like the teeth of a saw.

This is the Great Wall of Kabul. And according to local lore, it holds terrible secrets.

The legend is usually dated to the 6th or 7th century, when Kabul’s ruthless king allegedly forced his male subjects to build the Great Wall to protect the city from invaders. Those who would not work on the wall were sealed inside it.

“Maybe something like that happened,” said Aziz Ahmed Panjshiri, a historian. “We have many legends about the cruel king. But it belongs to history to make clear what was the reality.”

A few years ago, history got some help.

The discovery of a nearly 500-year-old skull in a destroyed section of the Great Wall of Kabul in 2013 has renewed speculation about the fate of the country’s “cruel king.” (Courtesy of Mohammad Younas Nawandish)

In April 2013, heavy rains caused a section of the wall to collapse. Amid the damp dirt shone something smooth and pale.

It was a human skull.

The discovery added some weight to what previously had been a tall but rather thin tale.

[Kabul’s car-bomb graveyard is a monument to years of bloodshed]

“This skull shows that the stories were true,” said Abdul Ahad Abassy, director of Afghanistan’s Department of Historical Monuments.

Science, however, has added another twist to the legend of Kabul’s cruel king.

Experts in Germany determined that the skull is not, in fact, 1,500 years old. Instead, it is about a third that age. The revelation has thrown the legend for a loop.

“They sent it back and said, ‘This is not old,’ ” Panjshiri said.

Only in a country like Afghanistan, which is so layered with history that it wears its invasions like rings on a tree, could a nearly 500-year-old skull be scoffed at.

“Afghanistan is a very ancient country,” Panjshiri said. “It was the citadel of central Asia, the center of the Silk Road.”

The city of Balkh, in northern Afghanistan, is almost 5,700 years old, he said proudly. Known as Bactra, it was once one of the greatest cities on Earth — the center of a vast empire stretching from Greece in the west to India in the east.

Kabul’s Great Wall has its own long history. It was once used to keep out Muslim invaders, then Muslims used it to thwart their own enemies. In 1879, during the second Afghan-Anglo war, British colonialists destroyed a fort, Bala Hissar, connected to the wall. A century later, Afghan mujahideen backed by the United States and Britain used the wall in their efforts to resist Soviet occupiers. Today, only a fraction of the wall is still standing.

[Kabul’s blast walls protect a powerful few while causing misery for many]

Debate over the wall’s history has proved almost as intense as the history itself. Some scholars say it was built in the 5th century A.D. Most believe it was erected about 200 years later, but ­Panjshiri claims it is much older.

“This wall was a contemporary with the Great Wall of China,” he said, dating both structures to about 200 B.C. As evidence, he cites the ancient Greek geographer Strabo, who allegedly mentioned the wall in a book written 2,000 years ago.

Panjshiri’s research, however, is no match for the power of legend. In one popular parable, the wall was built in the 6th century by Zamburak Shah, a ruler so ruthless that his overworked subjects revolted, killing the king and burying him inside his own wall. Sometimes, the tale includes the flourish that it was a beautiful slave girl who fatally tricked the king.

The most common legend says the king entombed his tired or rebellious subjects in the wall with impunity. In true Afghan fashion, this version has no happy ending.

Three years ago, spring showers exposed the skull and other bones. In April 2013, Mohammad Younas Nawandish, then the mayor of Kabul, sent Panjshiri and a photographer to investigate.

Word spread around Kabul that the legend was true. But when German scientists analyzed the skull, and dated it to about A.D. 1550, a millennium after Zamburak Shah, it showed that at least that section of the wall had been built, or rebuilt, long after the rampart’s original construction, Panjshiri said.

The discovery of the skull has — disconcertingly to some — shifted attribution for the legendary act of cruelty to a line of popular Mughal kings who ruled Kabul in the 16th century. The greatest of these kings, known as Babur, was a hard-drinking warrior poet who loved Kabul so much that he was buried here.

But Thomas Barfield, an anthropology professor at Boston University, warned against using the skull to assign blame ex post facto, especially until more research is completed.

“When skeletons or skulls come up, it’s easy to weave stories around them,” he said, adding that such stories can be more useful and interesting in what they reveal about the present than the past. “Often they are comments on what is happening now, sometimes directly, but sometimes it is almost subconscious.”

Painting past kings as either good or evil — when the reality is usually somewhere in between — may serve moral or political agendas in a country that continues to be racked by war, he said.

Or it may just make for a good yarn.

“Sometimes archaeologists are considered spoilsports because they figure out that the story doesn’t quite fit,” Barfield said with a laugh. “Once again, science ruins a really good story.”

Read more:

The U.S. was supposed to leave Afghanistan by 2017. Now it might take decades.

Attack on Kabul restaurant leaves at least two dead, 15 injured

Afghan ‘Pentagon’ cost U.S. $155 million. A quake could level it, report finds.

Today's coverage from Post correspondents around the world