Sitting Bull in their land, as specified in the 1868 Treaty of Fort Laramie. It was alarmed at reports of Sioux depredations (encouraged by Sitting Bull). In November 1875, President Grant ordered all Sioux bands outside the Great Sioux Reservation to move onto the reservation, knowing full well that not all would comply. As of February 1, 1876, the Interior Department certified as "hostile" those bands who continued to live off the reservation. This certification allowed the military to pursue Sitting Bull and other Lakota bands as "hostiles". Based on tribal oral histories, historian Margot Liberty theorizes many Lakota bands allied with
Sitting Bull natives joined him for safety in numbers. His leadership had attracted warriors and families, creating an extensive village estimated at more than 10,000 people. Lt. Col. Custer came across this large camp on June 25, 1876. Sitting Bull did not take a direct military role in the ensuing battle; instead he acted as a spiritual leader. A week prior to the attack, he had performed the Sun Dance, in which he fasted and sacrificed over 100 pieces of flesh from his arms. Custer's 7th Cavalry advance party attacked Cheyenne and Lakota tribes at their camp on the Little Big Horn