It seems they're always deciding when different populations migrated to different parts of the world, then they find evidence it was more complicated than they imagined. All part of a puzzle, that we find more pieces of all of the time.
Still, unless they can find an eye witness, imagination will always have to play a part. Our roots are much deeper than we've discovered so far.

It may be that we have knowledge of less than 1% of all the circumstances of human existence. We assume we know so much.