information:classification, linguistic:paraphrasing
Land allotment

By the 1880s, the Dakota and Lakota tribes were fragmented onto reservations which diminished in size over time. They lost hundreds of thousands of acres by the 1920s. In 1887, the United States Congress passed the General Allotment Act (Dawes Act), which began the assimilation of Dakota and Lakota people by forcing them to give up their traditional way of life. The Dawes Act ended traditional systems of land tenure, forcing tribes to adapt government-imposed systems of private property and to "assume a capitalist and proprietary relationship with property" that did not previously exist. In 1889, North Dakota and South Dakota were holding statehood conventions and demanded reduction of the Great Sioux Reservation, which was established by the Fort Laramie Treaty of 1868. Just months before those states were admitted to the Union in November 1889, Congress had passed an act which partitioned the Great Sioux Reservation into five smaller reservations,. Tribal leaders such as John Grass, Gall, and Sitting Bull opposed the bill, which created the following five reservations:

After the boundaries of these five reservations was established, the government opened up approximately 9 million acres (36,000 km), one-half of the former Great Sioux Reservation, for public purchase for ranching and homesteading. Much of the area was not homesteaded until the 1910s, after the Enlarged Homestead Act increased allocations to 320 acres (1.3 km) for "semi-arid land".