Did Africans once independently invent the smelting of metals or did they obtain this technology from Europe or the Middle East? This continues to be an unresolved and hotly disputed issue, mainly because the dates for the earliest appearance of smelting in Africa south of the Sahara remain inconclusive. All the earliest sites in Western and West-Central Africa from Walalde in Senegal to the Tigidit cliffs and Termit in Niger, the firki plains south of lake Chad, Taruga, and perhaps Nsukka in Nigeria, Ghwa Kiva (Nigeria), and Doulo (Cameroon) in the Mandara mountains, Gbabiri (Ndio district) in the Central African Republic, and a few sites in Rwanda, Burundi, and Buhaya cannot be dated more closely than between 840 and 420 BCE. Greater precision is impossible because the C14 curve runs flat during these four centuries, hence all these sites yield the same date. (Alpern, Killick, Me Eachern, Holl, Jézégou/Clist, Kanimba Misago). If the earliest “real” dates fell before 800 BCE, they would support independent invention, while later dates strengthen the case for borrowing. Still, this information does tell us that ironworking was adopted in the northern parts of West and West -Central Africa and in the region of the Great Lakes within the span of a mere four centuries.
The emergence of ironworking must have left linguistic traces in the relevant terminology irrespective of whether it spread by borrowing or by independent invention—hence historical linguistics can contribute to this debate. That approach is best tested by an examination of the relevant vocabulary in Bantu languages because the historical study of those languages is further advanced than that of any other language family in Africa (Nurse/Phillipson). Moreover Bantu-speakers occupy a large portion of the continent.