Nok culture artifacts have been dated as far back as 790 BCE, located at the Jos Plateau in Nigeria, between the Niger and Benue River. From the excavation of the Nok settlement in Samun Dikiya, there was the tendency to build on peaks. Nok settlements have not been extensively excavated.[8] Sao Civilization Sites of walled city settlements in the lake Chad region (centered by the Chari River).