During the 1850s, whites exploited natives through illegitimate negotiations, which resulted in tribes being forced into separate designated reservations, dividing the tribes and making it easier for the government to control them.
The combination of the reduction of the Great Plains due to settlement and the Bureau of Indian Affairs's encouragement to hunt buffalo eventually led to the animal's dwindling population. This adversely affected the Indians' source of food and supplies.
Ghost Dance & Wounded Knee (1890)
Conflicts between the Indians and whites often resulted in the thorough defeat of the tribes involved. At Sand Creek, whites massacred over 100 of Black Kettle's Arapho and Cheyenne who believed that they were under protections. At Little Bighorn, whites fought and defeated the Sioux for leaving their reservation, forcing them back to their reservation.
Dawes Act (1887)
Whites began to hunt Indians for sport. Some offered rewards for bounty hunters who brought back heads of Indians. These acts were often under the goal of completely eliminating the tribes, which was motivated by the idea that coexisting with Indians was impossible.
The Ghost Dance was a spiritual movement that prophesied the retreat of the whites and the restoration of the buffalo population. Whites believed it was a warning for hostilities, so the Seventh Cavalry attacked the Sioux Indians at Wounded Knee, South Dakota. 300 Indians and 40 whites were killed in the conflict.
The Dawes Severalty Act was an approach to try to assimilate the western Indians into society. It provided the elimination of tribal ownership of land in place of individual ownership. Plots of land were given to each person, and some Indian children were taken away to schools which tried to abandon tribal ideals and instill Christianity.