Premise: The Ohio Valley Siouan, or Southeastern Siouan, languages are a subfamily of the Western Siouan languages, far to the east and south of the Mississippi River. The group has Ofo and Biloxi, in the Lower Mississippi River valley, and Tutelo, historically spoken in Virginia, near the territory of the Catawban languages. All of the languages are now extinct.
Hypothesis: The Ohio Valley Siouan has speakers in the Ofo, Biloxi, and Tutelo area whose span covers the Lower Mississippi River valley and all the way to Virginia.