Progressive Vowel Height Harmony in Proto-Kikongo and Proto-Bantu

The systematic comparison of the different types of progressive Vowel Height Harmony (pVHH) attested within the Kikongo Language Cluster (KLC) leads to the conclusion that this common Bantu process of long-distance assimilation cannot be reconstructed to Proto-Kikongo. The '(a)symmetric-pVHH' and 'back-pVHH' patterns, the two main and structurally different kinds of pVHH within the KLC, emerged independently and relatively late within two distinct subgroups, viz. South Kikongo and North Kikongo respectively. Moreover, the '(a)symmetric-pVHH' pattern further spread from a South Kikongo focal area coinciding with the heartland of the Kongo kingdom to other parts of the KLC through contact-induced dialectal diffusion. Furthermore, the historical-comparative evidence from the KLC suggests that neither symmetric nor asymmetric pVHH should be reconstructed to Proto-Bantu, the most recent common ancestor of all Bantu languages.