were steadily pushed westward by the tide of civilization to the Great Plains north of the Platte, where they claimed as their own all the vast region west of the Missouri as far as they could roam or fight their way. They resisted the approach of all settlers and opposed the building of the Pacific Railroad.
In 1867, Congress sent out four civilians and three army officers as Peace Commissioners, who, in 1868, made a treaty with the Sioux, whereby for certain payments or stipulations, they agreed to surrender their claims to a vast tract of country, to live at peace with their neighbors, and to restrict themselves to a territory bounded south by Nebraska, west by the 104th meridian, and north by the 46th parallel of latitude—a territory as large as the State of Michigan. "They had the solemn pledge of the United States that they should be protected in the absolute and peaceable possession of the country thus set apart for them; and the constitution makes such treaties the highest of all authorities, and declares that they are binding upon every citizen."
In the western part of the Sioux territory, lying between the two forks of the Cheyenne River, is the Black Hills country with an area of four or five thousand square miles. Of the interior of this region up to 1874 nothing was known excepting from the indefinite reports of hunters who had penetrated therein. The arrival at a trading post of Indians who offered gold-dust for sale which they said was procured at the Black Hills, caused much excitement; and a military expedition of 1200 men was sent from Fort Lincoln in July 1874, to explore the Hills and ascertain if gold existed there. As was expected, no hostile enemy were encountered by the large expedition
