You mean the Navajo Nation? Could that have potentially become a state in its own right?
I was refering to just about any historical reservation made that included more than one nation. These were always created due to the arbitrary decisions of the United States. If the Indigenous typically had more of a say, there wouldn't be any way the Modoc would be tossed together with the Shasta for example. As I muttered, native populations with minimal contact with the US, like those of inland Alaska, would be more likely for a Nunavut clone than anywhere else, in my ignorant opinion.