There is no such thing under the Constitution for 'sovereign Indian states or nations' or any euphemisms. Wikipedia is parroting back faux federal common law not supported by the Constitution.
As of the Indian Citizenship Act of 1924, there are no more "Indians" within the original meaning of the Constitution...only U.S./State citizens with "Indian ancestry/race" entitled to no more and no less than every other non-Indian U.S./State citizen.  Politicians are lying to the citizenry of the United States.