The Clovis People.



The oldest Clovis site in North America is believed to be El Fin del Mundo in northwestern Sonora, Mexico, discovered during a 2007 survey. It features occupation dating around 13,390 calibrated years BP.



The most commonly held perspective on the end of the Clovis culture is that a decline in the availability of megafauna, combined with an overall increase in a less mobile population, led to local differentiation of lithic and cultural traditions across the Americas.

The Picts



Pictish recorded history begins in the Dark Ages. At that time, the Gaels of Dál Riata controlled what is now Argyll, as part of a kingdom straddling the sea between Britain and Ireland. The Angles of Bernicia, which merged with Deira to form Northumbria, overwhelmed the adjacent British kingdoms, and for much of the 7th century Northumbria was the most powerful kingdom in Britain.[14] The Picts were probably tributary to Northumbria until the reign of Bridei mac Beli, when, in 685, the Anglians suffered a defeat at the Battle of Dun Nechtain that halted their northward expansion. The Northumbrians continued to dominate southern Scotland for the remainder of the Pictish period.



“What is undoubtedly mysterious is the extraordinary disappearance of the culture of the Pictish people within the course of the first two or three generations of mac Alpin kings,” noted Michael Lynch in his book Scotland: a New History.

Cucuteni–Trypillia



Due partly to the fact that this took place before the written record of this region began, there have been a number of theories presented over the years to fill the gap of knowledge about how and why the end of the Cucuteni–Trypillia culture happened. These theories include invasions from various groups of people, a gradual cultural shift as more advanced societies settled in their region, and environmental collapse.

Sanxingdui Culture



In 1929, a peasant in Sichuan province, on the western borders of China's traditional territory, uncovered jade and stone artefacts whilst repairing a sewage ditch. This was a site that was located about forty kilometres (twenty-four miles) from Chengdu, but following these initial, accidental finds it was largely forgotten for second time. The significance of the jade and stone was not understood until 1986, when archaeologists unearthed two pits of Bronze Age treasures that included jades, about a hundred elephant tusks, and stunning, giant bronze sculptures 2.4 metres-high (eight feet) that suggest an impressive technical ability, one that was present nowhere else in the world at the time at which they were made.



"The current explanations for why it disappeared are war and flood, but both are not very convincing," Niannian Fan of Sichuan University told LiveScience. The discovery of the ancient city of Jinsha 40km southwest of Sanxindui deepened the mystery, but may also help solve it. Objects at Jinsha have very similar images on it to those found at Sangxingdui, suggesting the two civilizations were at least connected, and their ages suggest Jinsha have been Sangxingdui's successor.

Everyone has heard of the lost city of Atlantis but there are plenty of other civilizations throughout history that we know existed but do not know exactly why they vanished. Here are a few ancient civilizations from all over the world that mysteriously disappeared.Around 12,000 to 13,200 BC.The most mysterious aspect of the Clovis people is that there has only been ONE human burrial accociated with them. It was of an infant boy. DNA testing was done and it was found that 80 percent of all present-day indigenous people in North and South America are direct descendants of the family of the boy.The other 20 percent are more closely related to the Clovis than any other people on earth.The Clovis were great tool makers, especially credited with fluted spears aptly called the Clovis Point. Clovis sites have since been identified throughout much of the contiguous United States, Mexico, and Central America.Around 10,500 years ago, Clovis abruptly vanish. No one knows for sure why they disappeared.A very tough people from northern Scotland, they are the reason why Roman ruins are not found in the northern highlands. They were able to repel Roman advances. In fact, Romans are the reason they are called the Picts (meaning painted or tattooed people) and much of what we know about them is from Roman writings. They spoke a language that is now extinct and no one knows how to speak or translate it.Though not as old as other civilizations in this OP, it is still not known exactly what happened to the Picts.The first great civilization of Europe, The Cucuteni-Trypillia (CT) culture covered a massive area of what is now Ukraine and Romania 3500-4000 BC.They built some of the largest settlements in neolithic Europe. Some cities may have contained up to 46,000 people.The CT were forward thinking for their time as they had no political elite and no social stratification. Whats really weird is around every 60-80 years they would burn their own cities and rebuild them.There is a ton of info on this interesting culture, if you like to read more click HERE or HERE Around 12,000 BC, the discovery of this ancient Chinese culture has challenged the traditional story of how Chinese culture began. The Sanxingdui were exceptional at metal working. Their works include the oldest known life sized stature of a human.First discovered by a peasant in 1929. Imagine going out to fix a sewer and instead, discovering an ancient city.The culture mysteriously disappeared around 3000 years ago. No one knows for sure what happened but there are a few theories on what happened.This is another very interesting culture, if you'd like to read more about them, check out here here , or here. These are just a few examples of civilizations that have abruptly vanished throughout history. There are plenty of these to read about and if you would like here are more examples for you to keep boredom at bay today.