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.