[5] Nicolaï (1981) argued that Tagdal was originally derived from the Tuareg languages and adopted characteristics of Songhai rather than vice versa.

[6] There are two dialects: Tagdal proper, spoken by the Igdalen people, pastoralists who inhabit a region to the east along the Niger border to Tahoua in Niger,[4] and Tabarog, spoken by the Iberogan people of the Azawagh valley on the Niger–Mali border.

Rueck & Christiansen say that ...the Igdalen and the Iberogan have for many purposes been treated as one group, and their speech forms are closely related.

Nicolaï uses "tihishit" as a common designator for these two speech forms...; however, this term is ambiguous.

"Tihishit" is a term of Tamajaq origin meaning "the language of the blacks".