Lionel Bender (1980) proposes several Eastern Sudanic isoglosses (defining words), such as *kutuk "mouth", *(ko)TVS-(Vg) "three", and *ku-lug-ut or *kVl(t) "fish".
The putative Eastern Sudanic languages are "surprisingly diverse" and resemble in this the larger Nilo-Saharan proposal.
A set of head-initial languages corresponds largely with the Southern group (typologically similar to also e.g. the Kadu and Central Sudanic families), and a set of head-final languages corresponds largely with the Northern group (typologically similar to also e.g. the Maban and Saharan families).
Omotic and Cushitic, in particular, are nearby head-final families belonging instead in the large Afro-Asiatic phylum and forming the Ethiopian language area.
Lionel Bender assigns the languages into two branches, depending on whether the 1sg pronoun ("I") has a /k/ or an /n/: Nubian Nara Nyima Taman Surmic Eastern Jebel Temein (Nuba Hills) Daju Nilotic Claude Rilly (2009:2)[4] provides the following internal structure for the Eastern Sudanic languages.
Surmic, Nilotic, and Temein share a number of similarities, including in their pronouns, but not enough to warrant classifying them together in opposition to Astaboran without proper comparative work.
Nilotic Surmic Eastern Jebel Daju Temein Nubian Nara Taman Ama Dimmendaal & Jakobi (2020:394),[9] published in 2020 but written some times earlier, retains Bender's Southern branch; they also accept Berta: Taman Meroitic Nubian Nara Nyima Berta Jebel Daju Temeinian Surmic Nilotic Comparison of numerals in individual languages (excluding Nilotic and Surmic languages):[10]