The Bantu language family is a branch of larger language groups (e.g. Niger-Congo, Benue-Congo, Bantoid). The 400+ Bantu languages range from Cameroon in the northwest to Kenya in the northeast, and South Africa in the south. Bantu languages are conventionally referred to by a LETTER-NUMBER combination (like A12 or G44) following the Guthrie reference system (map and language list). This system uses the letters ABCDEFGHJKLMNPRS for zones, located approximately on this map from Wikimedia: The expansion of the Bantu languages is seen in the map below from Koile et al. (2022). Proto-Bantu (PB) is the reconstructed ancestor of all these language groups. Northwestern Bantu (NWB) languages are groups 1-2 in green. [Zones A, B10-30] Proto-Northwestern-Bantu (PNWB) is their reconstructed common ancestor. Transcontinental Bantu (TB) languages are groups 3-23. [Zones B40-80, C-S] Proto-Transcontinental-Bantu (PTB) is their reconstructed common ancestor. Eastern Bantu (EB) languages are groups 12-23 marked in red and orange. [parts of Zones D and H, Zones E-S] Proto-Eastern-Bantu (PEB) is their reconstructed common ancestor. South Bantu (SB) languages are groups 16-17. [Zones N20-40, P30] Proto-South-Bantu (PSB) is their reconstructed common ancestor. The Bantu family tree (based on lexical innovations) is seen in this chart from Koile et al. (2022): A more detailed chart would show even more little branches coming off the backbone of the long migration from present Cameroon to South Africa. To simplify the total number of branches, the convention of this dictionary is to define Eastern Bantu at node #3 where it still included the ancestors of the South-Western languages (most of zones KLR), reflecting their common dispersion somewhere along or west of the lakes area.
