Siouan languages
Authors who call the entire family "Siouan" distinguish the two branches as "Western Siouan" and "Eastern Siouan" or as "Siouan-proper" and "Catawban". Others restrict the name "Siouan" to the western branch and use the name "Siouan–Catawban" for the entire family. Generally, however, the name "Siouan" is used without distinction.
Assiniboine language
Sioux, Assiniboine, and Stoney are closely related languages of the Dakota family. Many linguists consider Assiniboine and Stoney to be dialects. However, they are mutually unintelligible. Parks and DeMallie report that they are not variant forms of a single dialect, but that Assiniboine is closer to the Sioux dialects than it is to Stoney. The exact number of interrelationships among the subdialects and dialects comprising this continuum is unknown.