Kanem-Bornu Empire
The Bornu Caliphate, which was headed by the Bornu Emperors, began in 1472. A rump state of the larger Kanem-Bornu Empire, its rulers held the title of Caliph until 1893, when it was absorbed into the British Colony of Nigeria and Northern Cameroones Protectorate. The British recognized them as the 'Sultans of Bornu,' one step down in Muslim royal titles. After Nigeria became independent, its rulers became the 'Emirs of Bornu,' another step down.