It's going to be interesting to see what the Russians say about this. Western historians say that Russia was founded by Vikings that settled in East Europe and took leadership of the Slavs they found there (and interbred with them). Soviet historians always said Nope, Slavs developed on their own, with no help from any vikings, thank you. What are they going to say? That these people were just passing through?
Professor Stephan Oppenheimer says that about 50% of Europeans can trace their DNA to one man in the Indus Valley who made their way to Europe through the Middle East. The other (about) 50% can trace their DNA to a son of the same man who made their way to Europe through Russia a thousand years later.
It is my opinion that Europeans can trace their origins to the Gansu Province of China...many thousands of years ago. And, perhaps even further east. Think Ainu/Jomon of Japan.
During the Ice Age Europe was covered by huge layers of Ice and the Last Glacial Maximum(LGM)18,000-23,000 years ago was the coldest time of the entire Ice Age and is probably what killed the Neanderthals in Europe.
So, where were the Europeans during this time? Look east, young man.