The rich morphological systems and discourse-based syntactic structures of a range of modern Bantu languages have attracted the attention of many linguists. The present contribution takes articles in a volume on the reconstruction of Proto-Bantu grammar edited by Bostoen et al. (2022. On Reconstructing Proto-Bantu Grammar, Niger-Congo Comparative Studies 4. Berlin: Language Science Press. 808 pp. https://doi.org/10.5281/zenodo.7560553) as a basis, in order to address the origin of these grammatical properties. More specifically, historical as well as synchronic features of Bantu languages are compared with Tima, a related language spoken in the Nuba Mountains, Sudan, and classified as a member of the Kordofanian family within Niger-Congo by Greenberg. Contrary to a popular view, it is claimed here that subject inversion and corresponding (extended) ergative alignment marking with transitive verbs is not only a property of Tima as a Niger-Congo language, but also of several Niger-Congo languages classified as Bantu. Tima consequently may perform a role similar to that of Tocharian in the history of Indo-European studies. The present contribution also raises methodological issues related to lexicon-based Bayesian phylogenetics as against Greenberg’s method of multilateral comparisons, and the historical-comparative method. In addition, it addresses the question of the extent to which the spread of typological features coincides with so-called “belts” postulated in the typological literature on African languages.