Siouan languages
Siouan languages can be grouped into the Western Siouan languages and Catawban languages. The Western Siouan languages can be divided into Missouri River languages (such as Crow and Hidatsa), Mandan, Mississippi River languages (such as Dakotan, Chiwere-Winnebago, and Dhegihan languages), and Ohio Valley Siouan branches. The Catawban languages consist only of Catawban and Woccon.
Yuchi language
Yuchi is classified as a language isolate, because it is not known to be related to any other language. Various linguists have made claims, however, that the language has a distant relationship with the Siouan family: Sapir in 1921 and 1929, Haas in 1951, and 1964, Elmendorf in 1964, Rudus in 1974, and Crawford in 1979.