1809, name of a group of native peoples from the American plains speaking a Siouan language, from Dakota dakhota "friendly" (the name often is translated as "allies"). Recorded by Lewis and Clark (1804) as Dar co tar; in western dialects of the Teton subgroup, Lakota, Lakhota; in Assiniboine dialect, Nakota, Nakhota. The north-central U.S. Dakota Territory was organized in 1861 and divided into North and South and admitted as two states in 1889. Related: Dakotan.