Muslim religious leader and founder of the Sokoto Caliphate in what is now northern Nigeria. A Fulani born in the Hausa state of Gobir, Usman dan Fodio studied the Koran with his father, an eminent scholar, then moved from place to place to study with other religious scholars. When he was 25, he began teaching and preaching, and from this time his reputation as a holy man grew. He taught Islam in Gobir, and he was probably engaged as tutor to the future sultan Yunfa because of his learned reputation. Usman criticized the Hausa ruling elite for their heavy taxation and other practices that he claimed violated Islamic law. His call for Islamic reform (and tax reduction) earned him a wide following in the 1780s and 1790s, when he became a political threat to Gobir sultan Nafata. When Yunfa assumed power as sultan in 1802, the repression of Usman's followers worsened. Following the example of the prophet Muhammad, Usman went on a hijrah (spiritual migration), was elected imam (leader) of the reformist Muslims, and launched the jihad (holy war) that would bring down the Hausa royalty. In the conquered areas, Usman set up emirates whose leaders acknowledged his religious sovereignty, and in October 1808 the Gobir capital, Alkalawa, fell. In former Gobir, Usman established a new capital, Sokoto, from which he ruled virtually all of Hausaland. After 1812 Usman withdrew into private life, writing many works on the proper conduct of the pious Islamic community. After his death in 1817, his son Muhammad Bello succeeded him as the ruler of the Sokoto Caliphate, then the largest state in Africa south of the Sahara.