The lexifier is Ngbandi (I have used this name even though this name is not used of any language in the Central African Republic). The varieties of Ngbandi on both sides of the Ubangi River (the Central African Republic and the Democratic Republic of Congo) are called "Sango" (dialect of Ngbandi) and "Yakoma", which are probably not very different from those immediately south of them in the Democratic Republic of Congo.