In the late 1800s the federal government attempted to place all Plain Indians on reservations most of which were located in which state?

In the late 1800s, the federal government primarily placed many Plains Indians on reservations located in South Dakota. The Great Sioux Reservation was one of the most significant, encompassing a large area of the state. This effort aimed to confine Native American tribes to specific areas, often resulting in significant loss of land and cultural disruption.