Chiwere Siouan Chiwere Siouan is the heritage language of the Otoe-Missouria Tribe of Oklahoma and the Iowa Tribe of Oklahoma. It is the language of the Indians from whom the name of the State of Missouri was taken. It belongs to the Siouan family of Native American langanges and is most closely related to Winnebago, Kansa, Osage, and Omaha-Ponca. [eng]