This treaty, also known as the Blackfoot Peace Treaty and the Judith River Treaty, was signed on October 17, 1855. The gathering was dominated by the bands of the Blackfeet and their allies the Gros Ventre, who had been encouraged by the U.S. to meet with representatives from tribes west of the Continental Divide in order to establish peaceful relations.

Parties to the treaty that comprised the “western tribes” were the Flathead (Salish), Pend d’Oreille, Kootenai, and the Nez Perce. Thousands of people from the western tribes attended. Assiniboine sent messages, but did not attend, and the Crow were never notified because they could not be located by the commissioner’s representatives.

Tribal territories were mapped out and the Blackfoot Nation agreed that certain lands assigned them by the Treaty of Fort Laramie would be shared for 99 years as common hunting ground; the Missouri headwaters region was to be shared with the western tribes and the lands east of the Milk River were to be shared with the Assiniboine. No lands were ceded to the U.S. through this treaty.