Indian Territory, a portion of the region originally set apart by the United States government as a home for Indian tribes, is bounded by Kansas, Missouri, Arkansas, Texas, and in 1906 was incorporated with Oklahoma, then made into a state. The Cherokee Outlet, S. of Kansas, is sometimes described as a part of Indian Territory, although it is under the jurisdiction of Oklahoma (q.v.). The area, not including the Cherokee Outlet, is 31,000 sq. m. The surface'of the territory consists mainly of rolling prairie land rising gradually from the south-east toward the N. and W. In the south-east the surface is broken by low ranges of the Ozark Mountains which cross the Arkansas border. In the southwest are the Arbuckle Mountains. The mineral resources are practically undeveloped, but coal, copper, iron, marble, and building-stones are known to exist in considerable quantities. The territory is well watered, and is drained by the Red and Arkansas Rivers and their numerous tributaries. The river-bottoms are wide and fertile, subject to overflow in the spring. The Indian Territory, designed for occupation by all the tribes east of the Mississippi, originally extended west to 100°, and included portions of Kansas and Nebraska. In 1833 and 1834 the Creeks, Choctaws, Chickasaws, and Cherokees were removed hither ; the Seminoles in 1838, and portions of tribes from west of the Mississippi have been subsequently settled there. By purchase or consent of the Indians the territory has been gradually reduced to its present limits, Oklahoma (q.v.) having been thrown open in 1890. Most of the tribes have made considerable progress in civilisation, and have farms, schools., churches, etc. There are three districts. Pop. (1900) 392,060, of which total 97 per cent. is distributed amongst four of the five Indian civilised nations.