 In 1832, at the conclusion of the Black Hawk War, the Sac and Fox conceded the eastern section of Iowa and the western section of Illinois.In the terms the 12 mile stretch between the end of the Sullivan Line and the Mississippi was conceded (in what was called Half Breed Tract because it was to be set aside for mixed race residents).In 1836, the western boundary of the Sullivan Line latitude was extended 45 miles west to the Missouri River just south of Hamburg, Iowa when the federal government relocated the already relocated tribes further west in the Platte Purchase.