section_path: History/Prehistory
section_name: Prehistory
paragraph_text: Prehistory
  
  Kainji Dam excavations showed ironworking by the 2nd century BC. The transition from Neolithic times to the Iron Age was accomplished without intermediate bronze production. Some have suggested the technology moved west from the Nile Valley. But the Iron Age in the Niger River valley and the forest region appears to predate the introduction of metallurgy in the upper savanna by more than 800 years, as well as predating it in the Nile Valley. More recent research suggests that iron metallurgy was developed independently in sub-Saharan Africa.
  
  The Nok civilization thrived between 1,500 BC and AD 200. It produced life-sized terracotta figures that are some of the earliest known sculptures in sub-Saharan Africa and smelted iron by about 550 BC and possibly a few centuries earlier. Evidence of iron smelting has also been excavated at sites in the Nsukka region of southeast Nigeria: dating to 2000 BC at the site of Lejja and to 750 BC and at the site of Opi.