The Walla Walla and Umatilla are river peoples among many who shared the Big River (Columbia). The Cayuse lived along the tributary river valleys in the Blue Mountains. The Tribes lived around the confluence of the Yakama, Snake, and Walla Walla rivers with the Columbia River.

The river system was the lifeblood of the people and it linked many different people by trade, marriage, conflict, and politics. The people fished, traded, and traveled along the river in canoes and over land by foot.

The Umatilla occupied both sides of the Columbia River from above the junction of the Umatilla River downstream to the vicinity of Willow Creek on the Oregon side and to Rock Creek on the Washington side. The river people were tied with other Tribes along the river with close family, trade, and economic interests in the Columbia River Gorge and the northern Plateau.

The Walla Walla and the Umatilla were a part of the larger culture of Shahaptian speaking river people of southeastern Washington, Northeastern Oregon, and Western Idaho.

The Cayuse, whose original language is known to linguists as Waiilatpuan, lived: "..south of and between the Nez Perces and Wallah-Wallahs, extending from the Des Chutes or Wawanui river to the eastern side of the Blue Mountains. It [their country] is almost entirely in Oregon, a small part only, upon the upper Wallah-Wallah river, lying within Washington Territory."