Bornu (bôrˈnō) [key], former Muslim state, mostly in NE Nigeria, extending S and W of Lake Chad. It began its existence as a separate state in the late 14th cent. From the 14th to the 18th cent. Bornu exported slaves, eunuchs, fabrics dyed with saffron, and other goods to N Africa. Bornu reached its peak under the mai (ruler) Idris Alawma (ruled 1570–1610), when it was the leading state in the central Sudan region. Bornu declined from the 17th cent. In the early 19th cent. it was severely threatened by the Fulani but maintained its independence when Muhammad al-Kanemi (ruled 1814–35), who established a new dynasty, revived the state. However, Bornu began to decline again after c.1850 because of weak rulers, and was conquered (1893–96) by the forces of Rabih al-Zubayr, a Sudanese slave trader. In 1898, Bornu was divided among Great Britain, France, and Germany. In 1922 the German portion became part of the British Cameroons mandate of the League of Nations.