The Sokoto Caliph was the ruler of the Sokoto Caliphate. The official title is Sultan of Sokoto and includes the title "Amir-ul-Momineen". The post has become increasingly ceremonial since British rule, but the Sultan, considered a spiritual leader in the Muslim community in Nigeria, can still carry a lot of weight with Fulani and Hausa people from northern Nigeria.
Shaihu Usman dan Fodio, the founder of the dynasty of Sokoto State and of the Fulani Empire (consisting of the Fulbe Jihad states of which Sokoto was suzerain), never used the high style of Sultan (his son was the first to do so), but was simply titled Amir al-Mu´minin, also styled Lamido Julbe (which literally means Governor of the believers in Fulani). The sultan of Sokoto is the leader of the Qadiriyya sufi order, historically the most important Muslim position in Nigeria and senior to the Emir of Kano, the leader of the less populous Tijaniyya sufi order.
As mentioned above, the Sultans were also styled Amir al-Mu´minin and Sarkin Musulmi ("King of the Muslims", basically the autochthonous form of the former, which is the Arabic style of Caliphs and other independent sovereign Muslim rulers that claim legitimacy from a community of Muslims); Mai, occurring in various Sultans' surnames, is another autochthonous title.