 In 1855, Washington Territorial Governor Isaac Stevens negotiated the Hellgate treaty between the United States government and the Salish, Pend d'Oreille, and Kootenai people of western Montana, which established boundaries for the tribal nations.The treaty was ratified in 1859.While the treaty established what later became the Flathead Indian Reservation, trouble with interpreters and confusion over the terms of the treaty led Whites to believe the Bitterroot Valley was opened to settlement, but the tribal nations disputed those provisions.