They were labeled "G1" in Joseph Greenberg's Adamawa language-family proposal and later placed in a Waja–Jen branch of that family.
Guldemann (2018) observes significant internal lexical diversity within Tula-Waja, partly as a result of word tabooing accelerating lexical change.
Kleinewillinghöfer considers Tso and Cham to be branches that had diverged earlier.
Waja is considered by Kleinewillinghöfer to be a distinct branch, although its exact position within Tula-Waja remains uncertain.
[2] Below is a list of language names, populations, and locations from Blench (2019).