Proto-Bantu language

Proto-Bantu is the reconstructed common ancestor of the Bantu languages, a subgroup of the Southern Bantoid languages. It is thought to have originally been spoken in West/Central Africa in the area of what is now Cameroon. About 6,000 years ago, it split off from Proto-Southern Bantoid when the Bantu expansion began to the south and east. Two theories have been put forward about the way the languages expanded: one is that the Bantu-speaking people moved first to the Congo region and then a branch split off and moved to East Africa; the other (more likely) is that the two groups split from the beginning, one moving to the Congo region, and the other to East Africa.

Like other proto-languages, there is no record of Proto-Bantu. Its words and pronunciation have been reconstructed by linguists. From the common vocabulary which has been reconstructed on the basis of present-day Bantu languages, it appears that agriculture, fishing, and the use of boats were already known to the Bantu people before their expansion began, but iron-working was still unknown. This places the date of the start of the expansion somewhere between 3000 BC and 800 BC.

A minority view casts doubt on whether Proto-Bantu, as a unified language, actually existed in the time before the Bantu expansion, or whether Proto-Bantu was not a single language but a group of related dialects. One scholar, Roger Blench, writes: "[...] [t]he argument from comparative linguistics which links the highly diverse languages of zone A to a genuine reconstruction is non-existent. Most claimed [P]roto-Bantu is either confined to particular subgroups, or is widely attested outside Bantu proper." According to this hypothesis, Bantu is actually a polyphyletic group that combines a number of smaller language families which ultimately belong to the (much larger) Southern Bantoid language family.

The homeland of Proto-Bantu was most likely in the upland forest fringes around the Sanaga and Nyong rivers of Southern Cameroon. It was formerly thought that proto-Bantu originated somewhere in the border region between Nigeria and Cameroon. However, new research revealed that was more likely the original area of Proto-Southern Bantoid, before it spread southwards into Cameroon long before Proto-Bantu emerged.

Proto-Bantu is generally reconstructed to have a relatively small inventory of 11 consonants and 7 vowels.

The above phonemes exhibited considerable allophony, and the exact realisation of many of them is unclear.

Consonants could not occur at the end of a syllable, only at its beginning. Thus, the syllable structure was generally V or CV, and there were only open syllables.

Consonant clusters did not occur except prenasalised consonants, which were sequences of a nasal and a following obstruent. They could occur anywhere a single consonant was permitted, including word-initially. Prenasalised voiceless consonants were rare, as most were voiced. The nasal's articulation adapted to the articulation of the following consonant so the nasal can be considered a single unspecified nasal phoneme (indicated as *N) which had four possible allophones. Conventionally, the labial prenasal is written *m while the others are written *n.