I think there were two one before the great worldwide catastrophe around 12,000 to 10,000 years ago (some places a flood and earthquakes and volcanoes in other places) and the other after the catastrophe. All mankind did not settle, the best estimate is four or five sets of people started civilization after the catastrophe in the Middle East, Egypt, India, China and South America. These civilizations were far ahead of anyone else on the planet. Could be help from the ABs.
You sound like a multiregionalist (like me). What is an AB?