Lejja is a community of 33 villages in Enugu State, southeastern Nigeria. Lejja is mainly inhabited by the Igbo people and is located on the edge of the Benue Plateau, which has rich laterite and basalt resources. Archaeological evidence of iron smelting in Lejja dates back to 2000 BC, making it one of the earliest and most important iron smelting sites in sub-Saharan Africa.
Otobo Ugwu Dunoka Square is a famous iron smelting site, which contains more than 800 cylindrical slag blocks, each weighing 34 to 57 kilograms. Most of the religious customs related to the monument in the square are associated with iron smelting activities, which together form an important intangible cultural heritage of Lejja in terms of politics, economy, judiciary, medicine, gender relations and other aspects. Archaeologists have discovered multiple ironmaking, residential and ritual sites in the Lejja area, providing historical evidence for understanding ancient ironmaking technology, religious customs and socio-political structures.
As one of the important sites for understanding the origins of ironmaking in Africa, Lejja's cultural heritage is increasingly threatened by modern urban development and cultural changes.