I actually think this came about when the government went on a rampage to try to eliminate the native tribes, instead of allowing them to live peacefully, which had been agreed to.
I have to disagree with you here. In fact, I believe the opposite. I believe it's the advantage of victimhood.
I live near the New York-New Jersey border. There is a group in the Ramapo Mountains who claim to be an Indian tribe who intermarried with Hessian Soldiers during the Revolution. The last "chief" of the "tribe" took a name so ridiculous that it could only have come from a 1950's B western. Of course, they wanted recognition so they could build a casino. They have not been recognized by the feds, and, in my opinion, correctly. In a former career I had extensive contact with many of them and I believe the whole thing was made up. The local paper, of course, bought into the the whole thing.
Seems like they could do some simple DNA testing to prove what they are. ???