(see also Upper Platte Agency)
Established in 1869, this agency is sometimes called Cheyenne Agency. The agency was located on the west bank of the Missouri River below the mouth of the Big Cheyenne River, about six miles from Fort Sully. The following Lakota bands settled at Cheyenne Agency: Miniconjou, Sihasapa, Oohenunpa, and Itazipco.
Headmen at this agency included: Lone Horn, Red Shirt, White Swan, Duck, and Big Foot of the Miniconju; Tall Mandan, Four Bears and Rattling Ribs of the Oohenunpa; and Burnt Face, Charger, Spotted Eagle and Bull Eagle of the Itazipco.
Today the reservation is located in north-central South Dakota in Dewey and Ziebach counties. The tribal land base is 1.4 million acres with the eastern boundary being the Missouri River. Major communities include Cherry Creek, Dupree, Eagle Butte, Green Grass, Iron Lightning, Lantry, LaPlant, Red Scaffold, Ridgeview, Thunder Butte, and White Horse. Arvol Looking Horse, 19th generation keeper of the Sacred Pipe of the Great Sioux Nation, lives at Green Grass.