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.
Sa'och language
Sa'och (, also, "Sauch") is an endangered, nearly extinct Pearic language of Cambodia and Thailand spoken only occasionally by a decreasing number of older adults. There are two dialects, one spoken in Veal Renh Village, Prey Nob District, Sihanoukville Province (formerly known as Kampong Som Province), Cambodia and the other in Kanchanaburi Province, Thailand. "Sa'och" is the Khmer exonym for the people and the language. The Sa'och, however, consider this label, which means "scarlet fever" or "pimply" in Khmer, pejorative and use the autonym "Chung" () to refer to themselves and their language.