The Umatilla nation was bordered by the Teninos (Tinaynuɫáma - "People of Tináynu") to the West and the Klickitats (X̣ʷáłx̣ʷayłáma - "Prairie People") to north, across the Columbia River. Also by their northern border were the Palouse, Wasco-Wishrams (Wasq̓ułáma - "People of Wasq̓ú"; Wɨ́šx̣amma - "People of Wɨ́šx̣aa/Wɨ́šx̣am (Spearfish)"). They had friendly Cayuse, and Walla Walla tribes to the east. Because their homeland lacked natural defenses, the Umatillas were attacked from the south by groups of Bannocks and Paiutes.
Linguistically, the Umatilla language is part of the Sahaptin division of the Penutian language family — closely related to other peoples of today's Eastern Oregon, Eastern Washington, and the Idaho panhandle. These included the Nez Percé (Šíwaniš - "Stranger"), Cayuse (Wáylatpu / Wáylatpuuma - "Ryegrass People, i.e. Cayuse People"), Walla Walla (Walawalałáma - "People of Walula region along Walla Walla River"), Palouse (Paluuspamá - "People of Palus") and the Yakima (Mamačatłáma - "Yakama People"). These peoples were ravaged by smallpox and other infectious diseases contracted from European colonists during the first half of the 19th century and their populations depleted, as they had no immunity.
In 1855 the inland Sahaptin-speaking nations were forced to surrender their historic homelands under treaty to the United States government, in exchange for territorial set-asides on reservations.
Today the Umatilla share land and a governmental structure with the Cayuse and the Walla Walla tribes as part of the federally recognized Confederated Tribes of the Umatilla Indian Reservation. Their reservation is located near Pendleton, Oregon and the Blue Mountains.
A number of places and geographic features have been named after the tribe, such as the Umatilla River, Umatilla County, and Umatilla National Forest. The impoundment of the Columbia River behind the John Day Dam is called Lake Umatilla.
- "Umatilla," in Barbara A. Leitch, A Concise Dictionary of Indian Tribes of North America. Algonac, MI: Reference Publications, Inc., 1979; pp. 490-491.
- Hines, Donald M. The Forgotten Tribes, Oral Tales of the Teninos and Adjacent Mid-Columbia River Indian Nations. Great Eagle Publishing. Issaquah, WA. 1991, p. 55.
- Trafzer, Clifford E. (Fall 2005). "Legacy of the Walla Walla Council, 1955". Oregon Historical Quarterly. 106 (3): 398–411. ISSN 0030-4727. Archived from the original on 2007-01-05.
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