For the most part they are still there if you look. Except for the mound builders of the Ohio Valley who over farmed their land and starved to death or left about 100 years before Columbus arrived.
The point I am trying to make, perhaps poorly, is that Tocqueville one-dimensional simple noble savage never existed. And basically it was Europeans sitting around their salons in Paris that created him.
I disagree in part. Of course the exaggerated image was made, and still remains today (though one wonders why living w/o our comforts is so attractive, no?); however, is there not an element of truth to it, more for the wandering tribes of the deep woods and the south Plains, perhaps? Did they not live and die in a way that at some fundamental level seems better than our way?