I don't see a time scale on the map. If you go back 18,000 years or so, there were no humans in North America. After that, there was a series of migrations from

I don't see a time scale on the map. If you go back 18,000 years or so, there were no humans in North America. After that, there was a series of migrations from Asia. Certainly, over time, distinct tribes formed, reformed, and disappeared, over varying areas, until we get the current map you see. It would be nice to see a time scale reflect this morphology.