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.
Shakori
The Shakori were associated with other Siouan tribes of the Piedmont, such as the Sissipahaw and Eno, and they all are believed to have spoken the same Siouan language. Scholars debate whether the Shakori, Eno, and Sissipahaw were different tribes or bands of the same tribe. This distinction became moot as the tribes merged with one another as their numbers decreased. Although they merged into remnants of other tribes and the larger Catawba, their Siouan dialect survived as late as 1743 among the Eno. They resisted Catawba assimilation the longest.