 However, the discovery in November 1858 of gold in the Rocky Mountains in Colorado (then part of the western Kansas Territory) brought on a gold rush and a consequent flood of white emigration across Cheyenne and Arapaho lands.Colorado territorial officials pressured federal authorities to redefine and reduce the extent of Indian treaty lands.On February 18, 1861, six chiefs of the Southern Cheyenne and four of the Arapaho signed the Treaty of Fort Wise with the United States at Bent's New Fort at Big Timbers near what is now Lamar, Colorado.