[WalterBright]

It's much like Europe and everyplace else - regular warfare and invasions and vast territories changing hands. The only difference is the people in Europe wrote things down.

(In contrast, very little is known about England for centuries after the Romans left, as the inhabitants were illiterate. Nobody knows if King Arthur existed or not, for example.)

DNA evidence has been slowly illuminating the pre-Columbian history of the North American Indians.