Former territory, U.S. West, including most of modern Oklahoma.
The Choctaw , Creek , Seminole , Cherokee , and Chickasaw tribes were forcibly moved to this area between 1830 and 1843, and an 1834 act set aside the land as Indian country. In 1866 its western half was ceded to the U.S.; this portion was opened to white settlers in 1889 and became the Territory of Oklahoma in 1890. The two territories were united and admitted to the Union as the state of Oklahoma in 1907.