Starting in 1794, Native American titles to Indiana lands were extinguished by usurpation, purchase, or war and treaty. The United States acquired land from the Native Americans in the 1809 treaty of Fort Wayne, and by the treaty of St. Mary's in 1818 considerably more territory became property of the government. This included the future Decatur County, which was authorized by the state legislature on 12 December 1821. No settler was allowed in the area until the government survey was completed in 1820.