The Proto-Dahu-Kemba language, the ancestor of the Dahu-Kemba language family, was spoken by the Proto-Dahu-Kemba people who lived in North-East Aheku until Omun Hemwan-186X (what we would call 1500 BC). OH -186X was the first of several years of migration for the PDK people.
They moved west to establish two new settlements, one in what is now Heiko and one in modern Pekau. Once the two colonies were established, their speech patterns began to diverge. Separate Dahu and Kemba languages were recognisable from somewhere around OH -1722 (i.e. 1300 BC).
Their language is known to us as Proto-Dahu-Kemba. What its speakers called it, though, is unknown. They kept no written records, so PDK is known to us only through reconstruction.
The traditional comparative method has proved difficult to apply as PDK only had two daughter languages. There are written records of both Dahu and Kemba, but where they diverge, it is not clear which, if either, is following PDK. Dahu though, had a sub-stratum influence from the Macro-Senduri languages. Kemba had no such influence and is therefore considered closer to PDK.
Nevertheless, a vocabulary of 1500 words can be reconstructed with some confidence. It consists mostly of words related to everyday activities, nature, sailing and agriculture.
Number vocabulary is of particular note. PDK counted in base 5, though all its modern descendants use base 12. Base 12 was an invention of mathematicians at the Kemba imperial court, during in the Classical Age.
Like all its descendants, Proto-Dahu-Kemba displayed accusative-secundative alignment. It also had a single genitive case (like present day Kemba languages, but unlike present day Dahu tongues).
The language was characterised by its velar and uvular consonants and moderately complex syllable patterns.
Morphologically, the language was moderately agglutinating. Mood and aspect were marked on the verb and possession was marked on the noun. Singular, dual and plural were marked on pronouns, as were three grades of politeness. Derivational morphology was less extensive than in classical and modern D-K languages, but some existed.
The use of classifiers was not yet established. The concept of classifiers was borrowed into Kemba from languages to the south.
PDK was known to favour Subject-Verb-Object word order in sentences and to put the noun first in noun phrases. Variant orders cannot be reconstructed with any confidence, though no doubt there were some.
We cannot yet claim to know much about the ancestor of PDK. A Pre-Proto-Dahu-Kemba language has been posited as the ancestor of the Dahu-Kemba and Macro-Senduri families plus a range of other languages. Like Modern Senduri, this was thought to have been a Verb-Subject-Object language with a trigger alignment. As yet though, the PPDK hypothesis remains highly conjectural.
The immediate descendants of Proto-Dahu-Kemba were, as noted, Dahu and Kemba. The former went on to divide into Eastern and Western Dahu. The former group includes Lemohai, the language of Mohai. In the modern era there are eight Dahu languages and six Kemba languages.