Blood quantum. The term itself seems a dodo, a relic of Third Reich Germany, sham science and miscegenation laws. But on reservations, enrolling in a tribe depends on your genetic history.

In Montana, the typical percentage used is .25, meaning that one-quarter of your genetic history must come from tribal members. That’s true on the Flathead reservation, the Crow reservation, and the Blackfeet reservation. Fort Peck and Fort Belknap reservations require that a tribal member have a .25-combined blood quantum of the two tribes that predominate on the reservation, Assiniboine and Sioux. On the Fort Belknap reservation, a tribal member must have .125 blood quantum combined of the Assiniboine or Gros Ventre tribes.

On the Rocky Boy Reservation, home to the Chippewa-Cree tribe, any child born to a tribal member on the reservation can enroll in the tribe, no matter who the other partner is. If that child is born off-reservation, he or she must have a .5 blood quantum.

The Northern Cheyenne tribe has the most liberal policy on tribal enrollment in Montana. You need only to have legal documents that prove direct descendency to enroll.