A purpose of the present study is an evaluation of various models of classification of the South branch of the Cushitic languages. The South Cushitic languages are studied in their narrow sense here, i.e. without Dahalo and Ma’a, although their probable cognates are registered.

A genetic subgrouping of 16 East Chadic languages is proposed in this paper. Contrary to the popular lexicostatistical approach, and in order to take into account potentially different rates of lexical evolution in the individual languages, it is attempted here to rely on the identification of common innovations. A practical method is presented how to apply the notion of common innovation when working with lexical isoglosses. This new method can also serve as a model for the subgrouping of language families other than East Chadic.

In the article the affiliation of Kujarke in genealogical classification is discussed. The Kujarke language is an isolate from Chad-Sudan neighborhood, described by the anthropologist Doornbos in 1981 (partially published in 1983). The present study operates with all c. 200 lexemes collected by Doornbos and evaluates their affinities in neighboring languages classified as Chadic and Nilo-Saharan. It is possible to conclude that Kujarke probably represents an independent group of East Chadic branch. From the neighboring Nilo-Saharan languages the strongest influence was identified from the Fur family.