Let me guess that by “advanced” you mean a society that has achieved mass food production. This is not meant to be nostalgic about hunter gatherer societies, but after reading the latest National Geograpic, heck even a recent issue for the New York Times, those hunter gatherer societies seem like they have one of the few ways of life that will be even viable in a hundred years or so.

I visited cahokia a few years ago, the ancient mounds there opened up my eyes to the rich history of native americans, I’d recommend a vist.