Survey Map of Oklahoma and Indian Territory showing distances, municipal towns, and post offices, published by George Cram, 1902 Most of the land that is now Oklahoma was acquired by the United States in 1803 as part of the Louisiana Purchase. In the 1830s, the U.S. used the land to relocate Indian tribes and the Indian Territory was formed from the land set aside by the Indian Intercourse Act of 1834. The Indian Territory originally extended beyond present-day Oklahoma, but the size was gradually reduced over the course of the 19th century. In 1889 Congress authorized the opening land seized from the Indian Territory for homestead settlement, and a year later Congress passed an act that officially created the Oklahoma Territory. RG 233, Records of the U.S. House of Representatives