The Nok culture of central Nigeria produced large hollow terracotta figures of striking sophistication and is among the earliest evidence for iron smelting in sub-Saharan Africa, with furnace and slag dates reaching deep into the first millennium BCE. Excavated smelting sites show clay furnaces used to win iron from local ore well before the technology was once assumed to have arrived from outside. The spread of iron tools transformed farming, forest clearance and population growth across West Africa. Nok's artistic tradition appears to lie behind later Yoruba and Benin sculpture.
Early African ironworking gave the continent the tools to clear land, intensify agriculture and support the denser settlement and trade that later cities depended on.