The Cayuse were originally located in northeastern Oregon and southeastern Washington state and lived adjacent to territory covered by the Nez Perce. The Cayuse were noted horsemen and often used their horse-riding prowess to intimidate other tribes. The Cayuse moved to the Umatilla Reservation after signing a treaty with the U.S. federal government in 1855.
The Cayuse language is considered to be an isolated, one-of-a-kind language that is a branch of the Penutian language group. The Cayuse call themselves the Te-taw-ken, which means "we, the people".