Milestones: 1800-Present

1800
By early 19th century, the Great Sioux Nation dominates the northern Plains, an area including most of the Dakotas, northern Nebraska, eastern Wyoming, and southeastern Montana
1803
The United States purchases the Louisiana Territory from France. The westward expansion that follows eventually leads to depletion of the buffalo, an animal central to the Lakota way of life.
1866-68
Red Cloud leads the successful fight to close off the Bozeman Trail, a pass leading to the gold mines of Montana. The trail crosses over the traditional hunting grounds of the Teton.
1868
The Fort Laramie Treaty of 1868 establishes the Great Sioux Reservation, encompassing most of present-day South Dakota west of the Missouri River, including the Black Hills. The U.S. Government pledges to keep whites out of this territory.
1874
An expedition led by Lt. Col. George A. Custer discovers gold in the Black Hills, sending a rush of prospectors to the area. As more and more whites enter the area, the Indian people defend their homes and way of life.
1876
On June 25, Custer attacks a large Indian encampment. Sitting Bull, Gall, Crazy Horse, and several Cheyenne leaders defeat Custer and the 7th Cavalry at the Battle of Little Big Horn. Custer loses his entire command of more than 200 men in the battle.

1889
An act by the U.S. Congress in March 1889 splits the Great Sioux Reservation into six smaller reservations. Some of the tribes begin performing the Ghost Dance, a religious ceremony thought to extinguish the whites, return the buffalo, and the former way of life. South Dakota is admitted to the union in November.
1890
Sitting Bull is murdered on the Standing Rock Reservation. Following this event, Big Foot and his Mnikowoju band flee to Pine Ridge to seek protection under Red Cloud. More than 250 members of Big Foot's band are massacred by the 7th Cavalry on Dec. 29 at Wounded Knee. The event is often described as the last major conflict between the U.S. Army and the Great Sioux Nation.
1924
The Citizenship Act of 1924 naturalizes Indians born within the territorial limits of the United States.
1934
The Indian Reorganization Act recognizes tribal governments as sovereign nations.
1973
Members of the American Indian Movement seize the village of Wounded Knee and occupy it for 71 days.
1990
South Dakota Governor George S. Mickelson and representatives of the state's nine tribal governments proclaim 1990 a Year of Reconciliation. A Century of Reconciliation is declared in 1991.