 However , the peace and freedom of the Native Americans did not last for long . The Great Sioux War of 1876 – 77 was sparked when American miners discovered gold in the Black Hills of western South Dakota and eastern Wyoming . These lands were originally set aside for Native American use by the Treaty of Fort <unk> . When the settlers <unk> onto the lands , they were attacked by Native Americans . U.S. troops were sent to the area to protect the miners , and drive out the natives from the new settlements . During this bloody period , both the Native Americans and the U.S. military won victories in major battles , resulting in the loss of nearly a thousand lives . The war eventually ended in an American victory , and the Black Hills were opened to settlement . Native Americans of that region were relocated to reservations in Wyoming and southeastern Montana . 
