The Nok culture appeared in Nigeria around 1500 BC and lasted approximately 2,000 year, disappearing around 500 AD for unknown circumstances.  Their terracotta remains, such as this terracotta figure head are named after the Ham village of Nok in Kaduna State of Nigeria, where their terracotta sculptures were first discovered around 1928.  Little is known about the Nok people other than through the discovery of their iron-smelting furnaces used to make iron tools for farming crops and weapons, and their terracotta sculptures. 

Reference: https://en.wikipedia.org/wiki/Nok_culture