Macro-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, the Macro-Siouan hypothesis based on relations among Siouan, Caddoan, and Iroquoian is not universally accepted as proven.
Sion District
Sion has a population () of . Most of the population () speaks French (31,488 or 85.1%) as their first language, German is the second most common (1,878 or 5.1%) and Portuguese is the third (1,029 or 2.8%). There are 915 people who speak Italian and 20 people who speak Romansh.