The Fort Belknap Reservation was established in 1888 in north-central Montana. It comprises a small portion of the vast ancestral territory of the Blackfoot Confederacy, which consisted of the Northern and Southern Piegan ("Poor Robes"), Kainah ("Blood"), and Siksika ("Black Feet") tribes and their historical allies, the Atsina or Aaniiih Nation ("Gros Ventre"). Their former territory extended across all of north-central and eastern Montana and portions of eastern North Dakota. Fort Belknap Reservation was named after William W. Belknap, the secretary of war in President Ulysses S. Grant's administration. Belknap was later impeached for corruption.