A bifurcate merging parental generation terminological system is reconstructed for Proto East Bantu as are a term for cross-cousin and terms for parent-in-law which were, literally, cross-cousin s father and cross-cousin s mother . Because Proto East Bantu, its daughter interstages considered and most of the extant daughter societies have this same kin term system and the modern daughter societies seem universally to have lineage systems, we conclude that the last 2500 years of Proto East Bantu and Proto East Bantu descended social organization was dominated by unilineal societies practicing preferential cross-cousin marriage. This ancient system and its hallmark kin terms survived shifts from matrilineal to patrilineal descent in the instance of those East Bantu subgroups at the northwest and southern fringes of East Bantu s distribution.