Before our white brothers came to civilize us we had no jails. Therefore we had no criminals. You can't have criminals without a jail. We had no locks or...

Most likely true. They were, however, this continent's first slavers and first bigots. They had no jails because they weren't necessary. Those who violated the rules of the tribe were simply killed.

I don't recall history ever citing a tribal society that dramatically improved the lives of it's members generation to generation. Maybe you have some facts to share?