KML file (edit • help)KML is from Wikidata The Great Sioux Reservation initially set aside land west of the Missouri River in South Dakota and Nebraska for the use of the Lakota Sioux, who had dominated this territory. The reservation was established in the Fort Laramie Treaty of 1868. It included all of present-day western South Dakota (commonly known as "West River" South Dakota) and modern Boyd County, Nebraska. This area was established by the United States as a reservation for the Teton Sioux, also known as the Lakota: the seven western bands of the "Seven Council Fires" (the Great Sioux Nation).