Mandan was initially thought to be closely related to
Hidatsa and
Crow. However, since Mandan has had
language contact with Hidatsa and Crow for many years, the exact relationship between Mandan and other Siouan languages (including Hidatsa and Crow) has been obscured and is currently undetermined. Thus, Mandan is most often considered to be a separate branch of the Siouan family. Mandan has two main
dialects: Nuptare and Nuetare. Only the Nuptare variety survived into the 20th century, and all speakers were bilingual in Hidatsa. In 1999, there were only six fluent speakers of Mandan still alive.
Edwin Benson, the last surviving fluent Mandan speaker, died in 2016. The language received much attention from White Americans because of the supposedly lighter skin color of the Mandan people, which they speculated was
due to an ultimate European origin. In the 1830s
Prince Maximilian of Wied spent more time recording Mandan over all other Siouan languages and prepared a comparison list of Mandan and
Welsh words (he thought that the Mandan might be displaced Welsh). The idea of a Mandan/Welsh connection was also supported by
George Catlin. Will and Spinden report that the
medicine men had their own secret language. ==Phonology==