Proto-Bantu language

Proto-Bantu is the reconstructed common ancestor of the 550 or so Bantu languages which are spread across Central and Southern Africa. It is thought to have originally been spoken in West/Central Africa in the area of what is now Cameroon. Approximately 3000–4000 years ago, it split off from other Niger–Congo languages 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.

Proto-Bantu is generally reconstructed to have a relatively small set of sounds 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 for the "pre-nasalised" consonants.

The so-called "pre-nasalised" consonants were sequences of a nasal and a following obstruent. They could occur anywhere a single consonant was permitted, including word-initially. Pre-nasalised 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 pre-nasal is written *m while the others are written *n.

...
Wikipedia