The Southern Nilotic languages are spoken mainly in western Kenya and northern Tanzania (with one of them, Kupsabiny or Sapiny, being spoken on the Ugandan side of Mount Elgon).
The Southern Nilotic languages are generally divided into two groups, Kalenjin and Tatogoa, although there is some uncertainty as to the internal coherence of the Kalenjin branch.
[citation needed] Proto-Kalenjin has been reconstructed by Franz Rottland (1979).
[2] Historically, Southern Nilotic has undergone extensive contact with a "missing" branch of East Cushitic that Heine (1979) refers to as Baz.
[3] Proto-Baz reconstructions proposed by Heine (1979),[4] with notes about corresponding East Cushitic and Proto-East Cushitic forms from Sasse (1979):[5]