PS: I want to add I don’t think this ancient proto civilization was traveling into space, etc. I think they were an advanced stone age civilization. No bronze or iron has been found earlier than the proposed dated - if they knew how to work iron and bronze the evidence would have long since been gone even by the time Sumeria rose up.
But most human stories seem to start around the time just before and after a great flood.. So humans remember the end of the Ice Age but not before it?
You would think the Ice Age would have been such a big deal it was remembered in some myth.