Early Indian treaty territories in Montana

A number of different Native Americans living in present-day Montana entered into treaties with the United States during the 19th Century.

[3]: 52  On October 17, 1855, area 398 became shared hunting grounds for "ninety-nine" years and the Blackfeet accepted camps of the Flathead, Upper Pend d'Oreille, Kootenay and Nez Perce, as well as whites, on the ranges.

Further, they allowed the Assiniboine to hunt on a part of their easternmost treaty range (area 565) bordering present-day North Dakota (indicated with a black line).

[1]: 736–740  The green area 399 is not included in the 1855 treaty territory of the Blackfeet, but it was first formally relinquished on July 5, 1873, by executive order.

With adjoining tribal areas outside Montana, the territory was claimed by "Methow, Okanagan, Kooteny, Pend d'Oreille, Colville, North Spokane, San Poeil, and other tribes".

[2]: 856–857 The combined areas show the westernmost land recognized as Arikara, Hidatsa and Mandan territory in the Treaty of Fort Laramie (1851).