 The Treaty of Medicine Lodge gave the land west of the Caddos and Wichitas to the Cheyenne and Arapaho tribes, They moved from Colorado in 1869.The Cheyenne-Arapaho Agency (later renamed the Darlington Agency) was established in 1870.Canadian County was formed in 1889 as County Four of Oklahoma Territory as part of the Oklahoma Organic Act, which created Oklahoma Territory from part of Indian Territory.