Western Siouan languages
The Western Siouan languages, also called Siouan proper or simply Siouan, are a large language family native to North America. They are closely related to the Catawban languages, sometimes called Eastern Siouan, and together with them constitute the Siouan (Siouan–Catawban) language family.
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.