In the beginning (HG stage) it was quite simply "us" and "not us" (a.k.a. "them").

Eventually as civilizations stretched their reach these categories became more defined. But the ulterior motive always remained; to set apart, validate the setting apart, and justify aggression, exploitation, etc.

At the most, genetic differentiations stand up to examination, but then only as to traits not potentials.
There was enough genetic infusion when the ancient civilizations brought home conquered peoples to procreate with to blur these “racial” lines.
With today's ability to freely be anyplace on the planet from anyplace on the planet in 72 hours or so, we are all, as a previous poster states, basically mutts anymore anyway.

No one but the Egyptians built ancient Egypt.
And they were probably as polyglot an important crossroads of civilization as any is today.

Jammer