Siouan languages
Siouan or Siouan–Catawban is a language family of North America that is located primarily in the Great Plains, Ohio and Mississippi valleys and southeastern North America with a few other languages in the east.
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.