From: Mark Odegard
From: Piotr Gasiorowskior there was a "companion flood" as a huge postglacial lake in W Siberia emptied into N Kazakhstan, flooding the Steppes.
The Ob and Yenisey catchments were blocked from the sea until relatively late in the retreat of the last Ice Age. Huge interconnected lakes formed at the glacial front. These lakes took their path to the sea via a much increased Aral and Caspian, the Euxine and then to the Med. Some maps I've seen suggest Aral-Caspian-Euxine were united as one huge fresh-water lake.One point of this is that from before the height of the last Ice Age on down, Europe and Asia had a serious water barrier between them. The Steppe was not an east-west transit corridor. Only after the Arctic Ocean opened up could man regularly move between Ukraine and Mongolia.