Yakima Indians, a tribe of the Shahaptian division of the Shapwailutan language family. They originally lived mainly along the Yakima River in what is now the state of Washington. In 1855 the United States made a treaty with the Yakima and 13 other tribes, which were to be confederated as the Yakima Nation under Kamaiakan as chief. Instead, Kamaiakan led the tribes in the Yakima War (1855–58). The Indians were at first successful, defeating U.S. Army forces in the Spokane country in May, 1858, but were finally defeated decisively at Four Lakes in September.
The tribes taking part were moved to the Yakima Reservation and became known as Yakimas. The original Yakima tribe lost its identity.