Scholars believe that these languages were spoken by Southern Cushitic agro-pastoralists from Ethiopia, who began migrating southward into the Great Rift Valley in the third millennium BC.
Kießling & Mous (2003) have proposed more specifically that they be linked to a Southern Lowland branch, together with Oromo, Somali, and Yaaku–Dullay.
Alagwa has become similar to Burunge through intense contact, and so had previously been classified as a Southern West Rift language.
[6] There was a now extinct member of the West Rift branch of south Cushitic called "Tale" (pronounced Tah-lay).
The Tale southern Cushites occupied a region in the southeastern part of Lake Victoria, just south of the Grumeti River in the Mara region and then expanded westward, stretching their territory to the south of Lake Victoria (avoiding the lowlands of the southern and western lakeshore and making use of ecological zones suitable for their pastoralism south of Lake Victoria) and then expanded north to southern side of the Kagera river in the Kagera Region.