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.
Waccamaw
Very little remains of the Waccamaw's ancestral Woccon language today, it was one of the two Catawban branches of the Siouan language family. The language was lost due to devastating population losses and social disruptions during the eighteenth and nineteenth centuries. It is attested today in a vocabulary of 143 words, printed in 1709.