Standing Rock Sioux Reservation

The Standing Rock Sioux Tribe of North & South Dakota controls the Standing Rock Reservation (Lakota: Íŋyaŋ Woslál Háŋ), which straddles the border between North and South Dakota in the United States, and is inhabited by ethnic "Hunkpapa and Sihasapa bands of Lakota Oyate and the Ihunktuwona and Pabaksa bands of the Dakota Oyate," as well as the Hunkpatina Dakota (Lower Yanktonai). The Ihanktonwana Dakota are the Upper Yanktonai, part of the collective of Wiciyena.

Source: Wikipedia — Standing Rock Sioux Reservation (CC BY-SA 4.0)