A United States territory, stretching southward from Kansas to the Red River, with Texas on the W. and Indian Territory on the E., is a third larger than Scotland, and presents a prairie surface crossed by the Arkansas, Cimarron, and Canadian Rivers, and rising to the Wichita Mountains in the S. There are many brackish streams; the rainfall is light, hence the soil can be cultivated only in parts. Ceded to the United States under restrictions by the tribes of the Indian Territory in 1866, there were various attempts by immigrants from neighbouring States to effect settlements in Oklahoma, which the Government frustrated by military interference, maintaining the treaty with the Indians till 1889, when it finally purchased from them their claim. At noon on April 22, 1889, the area was opened for settlement, and by twilight 50,000 had entered and taken possession of claims. The territory was organised in 1890; embedded in it lies the Cherokee Outlet, still held by the Indians, but on the extinction of their interests to revert to Oklahoma. The chief town is Oklahoma.