The beginning of the Iron Age south of the Congo rainforest: the first archaeological investigations around Idiofa (Congo), c. 146 BC - AD 1648

Archaeological investigations of the Idiofa region in the Kwilu Province of the Democratic Republic of Congo have yielded the earliest evidence for iron production, combined with ceramics and lithic artefacts, south of the Congo rainforest during the second century BC. Palaeoecological data show that the producers of this industry did not settle in open grasslands but in a habitat where the forests had started to undergo climate-induced degradation before their arrival. The Early Iron Age at Idiofa continues until the third century AD and is followed by a long hiatus that was not driven by climate change until the fifteenth century. Later Iron Age (LIA) pottery in the area, which dates to c. 1487-1648, is markedly distinct from that of the EIA in vessel forms, size, recipe and decoration. EIA pottery from Idiofa resembles most closely slightly younger Kay Ladio pottery (c. cal. AD 30-475) from the Lower Congo region further west, which is also associated with the first metallurgy there. Idiofa's LIA pottery is indicative of a fifteenth- through seventeenth-century exchange network between the Kamtsha and Kasai Rivers. These shifting dynamics in pottery production are reflected in the region's linguistic stratigraphy, which may contribute to the interdisciplinary reconstruction of the history of ancestral Bantu speakers south of the rainforest.