The Bua languages are a subgroup of the Mbum–Day subgroup of the Savanna languages spoken by fewer than 30,000 people in southern Chad in an area stretching roughly between the Chari River and the Guéra Massif.
Maurice Gaudefroy-Demombynes added Tunia and "Mana" (possibly an alternate name for Fanian) in 1907, forming a "Groupe Boa".
Later, Pairault (1965, 1969) added the more northerly Gula languages, Fanian, Koke, and Bolgo, allowing Samarin (1971) to define roughly the current membership of the Bua languages/Adamawa-13.
Most of these languages have lost the typical Niger–Congo noun class system (Goula Iro appears to have retained it to some degree.)
However, its former presence is betrayed by their quite complicated system of plural formation, combining internal ablaut with changes to final consonants and/or suffixation.