text: Iron metallurgy in Africa developed within Africa; though initially assumed to be of external origin, this assumption has been rendered untenable; archaeological evidence has increasingly supported an indigenous origin. Some recent studies date the inception of iron metallurgy in Africa between 3000 BCE and 2500 BCE. Archaeometallurgical scientific knowledge and technological development originated in numerous centers of Africa; the centers of origin were located in West Africa, Central Africa, and East Africa; consequently, as these origin centers are located within inner Africa, these archaeometallurgical developments are thus native African technologies. 
  Iron metallurgical development occurred 2631 BCE – 2458 BCE at Lejja, in Nigeria, 2136 BCE – 1921 BCE at Obui, in Central Africa Republic, 1895 BCE – 1370 BCE at Tchire Ouma 147, in Niger, and 1297 BCE – 1051 BCE at Dekpassanware, in Togo. Evidence exists for early iron metallurgy in parts of Nigeria, Cameroon, and Central Africa, possibly from as early as around 2,000 BCE. Iron metallurgy may have been independently developed in the Nok culture between the 9th century BCE and 550 BCE. The nearby Djenné-Djenno culture of the Niger Valley in Mali shows evidence of iron production from  250 BCE. The Bantu expansion spread the technology to Eastern and Southern Africa between 500 BCE and 400 CE, as shown in the Urewe culture.