They are not under United Nations, they have formed a nation of their own, I didn't read all the details, but take a quick look at the links, I think it was the last one that says they have their own Constitution.
I have always heard of the Cherokees as the Cherokee Nation.
Manhole Explosions Outside Manhattan Mall
http://abclocal.go.com/wabc/story?section=traffic&id=3696258
Thanks, granny, for the help. I checked out the links, and found some interesting information.