thumb|right|map of the umatilla indian reservation the umatilla indian reservation is an indian reservation in eastern oregon in the united states. the reservation is mostly located in umatilla county, with a very small part extending south into union county. it is managed by the three confederated tribes of the umatilla indian reservation. located near the city of pendleton on the north side of the blue mountains, the reservation was established for two sahaptin-speaking native american tribes: the umatilla and walla walla, and for the cayuse, whose language, now extinct, was an isolate. all the tribes historically inhabited the columbia plateau region. the tribes share land and a governmental structure as part of their confederation. ==geography, demographics and headquarters==  the reservation has a land area of 271.047 sq mi (702.009&nbsp;kmÂ²) and a tribal population of 2,927 as of the 2000 census. in addition, some 300 native americans from other regional tribes and 1500 non-natives live on the reservation."who we are" (january 2013), confederated tribes of the umatilla reservation the largest community is mission, which is the site of the tribal headquarters as well as the umatilla agency of the bureau of indian affairs. some bia agency offices serve more than one federally recognized tribe, but the umatilla agency exclusively serves the confederated tribes of the umatilla indian reservation (cuitr). ==history== the tribes developed the wildhorse casino resort on their reservation to generate revenues for their people. the casino is located near interstate 84. in 2006 it started cayuse technologies, to provide software development and related services. these enterprises employ 1,000 persons and have markedly reduced unemployment. pendleton photographer walter s. bowman photographed tribe members in the early 20th century.[http://li
American_Indian_reservations_in_Oregon Geography_of_Umatilla_County,_Oregon Geography_of_Union_County,_Oregon