Native Americans are in the process of redefining tribal identity that is causing great concern among Native people.
David Wilkins, a political scientist at the University of Minnesota and a member of North Carolina's Lumbee Tribe, traces most purges to four factors: internal political squabbles, stricter racial requirements for membership, punishment for gang or drug-related crime and, most often, during debates over sharing casino profits.
In Oliphant v Suquamish Indian Tribe (435 U.S. 191), a 1978 U.S. Supreme Court ruling said the federal government should not intervene in most tribal membership disputes, leaving appeals up to the tribes.
According to the National Indian Gaming Commission, tribal casinos generated $25 billion in revenue last year. Tribes often split the profits by making payments to members. Fewer members can mean a larger paycheck for those left.
There are organizations that can help displaced Native people. The American Indian Rights and Resources Organization is a group that lobbies against expelling tribe members.
It's not clear how many people have been removed from tribes in the last few years. There are 562 federally recognized tribes, and tribal governments are not required to report citizenship decisions. But the number is in the thousands.In
The Cherokee Nation voted in March to deny citizenship to an estimated 2,800 descendants of tribal slaves.
Clearly, there is a power struggle going on. The tribes have the power and the displaced do not.