The project's main objectives were:
[1] Uncovering the archaeological signature of the first Bantu speakers south of the rainforest in the West-Coastal Bantu (WCB) homeland straddling the Congo River north of Brazzaville and Kinshasa around 2,500 BP.
[2] Determining (a) whether an earlier expansion of Bantu speakers took place along the Atlantic coastline, (b) whether their languages disappeared due to the later spread of WCB, and (c) whether they left substrate traces still detectable in WCB.
[3] Establishing (a) whether new settlements interacted with autochthonous hunter-gatherers and (b) whether signs of this contact are still retrievable in archaeology, linguistics, and genetics.
[4] Gaining insights on the subsistence economies of the first settlers in the study area.
[5] Reconstructing (a) the impact of vegetation dynamics and (b) whether major changes in the natural environment were primarily climate-induced or anthropogenic.
As for [1], following our 2019 lexicon-based phylogeny, we developed a new hypothesis on the WCB homeland, i.e. significantly further east, more precisely between the Kasai and its Kamtsha affluent in the Kwilu province (DRC). After initial archaeological fieldwork near the Bateke Plateau, excavations happened further east from 2019 onwards, i.e. around Idiofa and Kikwit and along Kwilu-Kwa-Kasai-Kamtsha-Loange Rivers, all areas previously unexplored. Two major westward expansions out of the Lower Kasai region towards the Atlantic coast must have started relatively soon after the initial settlement of WCB speakers south of the Kasai River, namely during the Early Iron Age (ca. 400 BCE-700 CE).
As for [2], our historical-linguistic research has confirmed that the Atlantic Coast is an area where early WCB speakers settled as the latest. Only one archaeological mission happened in the Lower Congo region. Neither this fieldwork nor earlier KongoKing research has yielded evidence for settlement preceding the CE.
As for [3], the most straightforward evidence for contact and admixture with local Central-African hunter-gatherer populations comes from genetic data. No clear archaeological evidence for contact between local Central-African populations and Bantu-speaking settlers has been found, but several sites excavated by our team contribute to a better understanding of the Late Stone Age region, especially Mitshikila and Mukila. Our diachronic phonological research on substrate interference shows that the WCB-speaking populations who had remained in the homeland area of the Lower Kasai engaged in intensive language contact both during the Early Iron Age (ca. 400 BCE-700 CE) and the Late Iron Age (ca. 1400-1900 CE), involving both local hunter-gatherer groups and populations with more northern roots speaking non-Bantu languages.
As for [4], we documented around 1400 BP a mixed subsistence economy with hunting, fishing, and collecting crabs, bivalve, and gastropods on the Atlantic coast. More archaeobotanical data will be published in future publications. The possibility to reconstruct specific terms of several domesticated plants and animals in the most recent ancestor of WCB suggests that the earliest WCB speakers had become proficient food producers. Nevertheless, reconstructable vocabulary for wild plants and animals shows that farming and husbandry coexisted with collecting and hunting in their mixed subsistence economy.
As for [5], palaeoecological data from around Idiofa, i.e. carbon isotopes and phytoliths, show that the earliest settlers around Idiofa in the 2nd century BCE did not settle in open grasslands but in a habitat where the forests had started to undergo climate-induced degradation before their arrival. Reconstructable wild flora and fauna lexicon also suggests that the earliest WCB speakers operated in a tropical moist lowland forest environment, a habitat that is significantly distinct from the one prevailing today south of the Kasai River. Analyses on charcoal from the Lower Congo suggest that the earliest pottery producers at Muanda on the Atlantic Coast lived in a wooded savanna environment, with mangrove and gallery forests nearby.
