There's gotta' be a cold, dry period sometime about 4000BC that drives these people and the reindeer and muskox herds they lived on South into Mesopotamia and the Huang Ho/Yangtse river systems where they could, in short order, expand those systems (and their accounting methods) into hieroglyphic writing.
All the rest of civilization would then arise out of the settled living and agricultural traditions of the folks from the South.
However, a civilization without some form of writing is just short of being a civilization.
Note, by hypothesizing a cold, dry period we can neatly get rid of the settled traditions in Ukraine. Those folks would have simply died out or found themselves reduced to being hunter/gatherers unable to maintain settlements.
I kinda tend to think that “civilization” was the result of ancient folk using that special weed as a smoke source in their saunas.
Domesticated animals and cultivated crops so they wouldn’t have to go so far to get some munchies when they were stoned.