The American Indians

It's hard for me to keep in mind what might be the two most important facts about the original human settlers in the Americas. (1) By the time Columbus arrived here, the great majority of Indians lived in cities, some larger than any city in Europe. Most Indians were urban. And (2) while the Indians developed many different cultures, most lived in large rigidly structured (Stalinist?) societies ruled by small elites.

I also have trouble remembering that we don't know how the Indians got here. The old land-bridge theory no longer seems convincing to scientists, and no new theory has been substantiated.