The Klamath and Modoc believe that they entered the Southern Oregon region as one people, later separating as the Modoc settled farther to the south. That they spoke dialects of the same language provides some support for this belief. The earliest influences of European society were indirect, Primarily through trade relations with Northern Great Basin groups who had obtained horses and other goods from Plains tribes. Sustained contact began in 1826, and the Klamath were quickly drawn into a trading network with Whites and other Indian groups at The Dalles and other trading centers. Unlike many other groups, the Klamath did not suffer from European-introduced epidemic diseases nor from hostilities with White settlers.
In 1864 the Klamath entered into a treaty with the Federal government, ceding their aboriginal land in return for the over one-million-acre Klamath Reservation, where they were joined by the Modoc and Yahuskin Paiute. In 1866 the Klamath Agency was established, leading to federal government control of Klamath life that was to continue until termination in 1954. Beginning in 1895, reservation land began to be allotted to individual Klamath and later to Modocs who Returned from Oklahoma where they had been sent following their defeat by the federal government in the war of 1872-1873.
In the first half of the twentieth century, Klamath society underwent profound economic and political changes through contacts with neighboring Whites and the policies of the various federal agents who administered the reservation. During this same period, they were involved in a series of land claims and natural resource suits with the federal and state governments and local land companies. In August 1954 a majority of the Klamath agreed to a federal proposal to end federal oversight and administration of the reservation. This led to serious problems as federal and Bureau of Indian Affairs programs were ended, individual Klamath were awarded large cash payments, and many individuals lost a sense of Klamath identity. Beginning in 1964, the Klamath were involved in a series of legal battles about old land claims and the sale of the reservation land and were eventually awarded over $20 Million in settlements. Efforts to reverse termination and regain federal recognition as an Indian tribe have so far been unsuccessful.