Siouan languages
In the 19th century, Robert Latham suggested that the Siouan languages are related to the Caddoan and Iroquoian languages. In 1931, Louis Allen presented the first list of systematic correspondences between a set of 25 lexical items in Siouan and Iroquoian. In the 1960s and 1970s, Wallace Chafe further explored the link between Siouan and Caddoan languages. In the 1990s, Marianne Mithun compared the morphology and syntax of all the three families. At present, this Macro-Siouan hypothesis is not considered proved, and the similarities between the three families may instead be due to their protolanguages having been part of a sprachbund.
Nakota
Recently the Assiniboine and, especially, the Stoney have begun to minimize the historic separation from the Dakota. They have claimed some identity with the Sioux nation, although such a centralized unit no longer exists. Historically, the Siouan tribes were quite decentralized as well and operated independently in bands. The tendency can be seen on Alberta's Stoney official Internet sites, for example, in the self-designation of the "Alexis Nakota "Sioux" First Nation", or in the claim of the "Nakoda First Nation" to their Sioux ancestry and the value of their native language:
"As descendants of the great Sioux nations, the Stoney tribal members of today prefer to conduct their conversation and tribal business in the Siouan mother tongue". Saskatchewan's Assiniboine and Stoney tribes also claim identification with the Sioux tradition.