In about 3200 BC the two earliest civilizations develop in the region where the southwest Asia joins the northwest Africa. Great rivers are a crucial part of the story. The Sumerians settle in what is now southern Iraq, between the mouths of the Euphrates and the Tigris
After Bacon’s Rebellion, Virginia’s lawmakers began to make legal distinctions between “white” and “black” inhabitants. By permanently enslaving Virginians of African descent and giving poor white indentured servants and farmers some new rights and status, they hoped to separate the two groups and make it less likely that they would unite again in rebellion
I would say we have better technology, so they can take part of the DNA and see when they were around. How long it's been since a dinosaur in the Triassic Era walked the earth.