Europe's genetic history was unlocked by researchers this week with a new DNA-based study.
Researchers found that the modern European gene pool originated from about 4000 to 2000 years ago.
They also found a mysterious blip in European history with genetic markers suddenly ending 4,500 years ago, only to be replaced by others.
This end and rebirth remains a mystery to scientists.
"What is intriguing is that the genetic markers of this first pan-European culture, which was clearly very successful, were then suddenly replaced around 4,500 years ago, and we don't know why," said study author Alan Cooper, from the University of Adelaide in Australia.
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"Something major happened, and the hunt is now on to find out what that was."
The study used 39 ancient skeletons and extracted DNA from mitochondria to make their findings.
Two of the samples were from Italy and the rest from Germany.
Europe was initially populated about 35,000 years ago.
The second wave was in the Neolithic period by farmers from what is now the Middle East.
The findings were published in the journal Nature Communications.