and called the Flatiron Reservation, in reference to its triangular shape. The Reservation was created by treaty on ApA.D. Most of the reservation covers parts of five counties in northeastern South Dakota, while smaller parts are in two counties in southeastern North Dakota, United States. The Lake Traverse Indian Reservation is the homeland of the federally recognized Sisseton Wahpeton Oyate, a branch of the Santee Dakota group of Native Americans.
