This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
The Fulani cleric Usman dan Fodio had spent years preaching reform against the mixing of Islamic practice with traditional religion in the Hausa city state of Gobir, and paid for it with expulsion from the state. On 21 February 1804 Sultan Yunfa of Gobir declared war on him, and dan Fodio answered with a jihad rather than retreat further. Over the four years that followed his forces took Katsina and Daura, then Kano in 1807, then Gobir itself in 1809, the seat of the ruler who had driven him out.
What rose from those campaigns was the Sokoto Caliphate, a state built directly on the jihad's victories rather than assembled afterward by other hands. By the 1830s it stretched across more than thirty emirates, reaching from territory that is now Burkina Faso to territory that is now Cameroon, governed under the reform dan Fodio had once been exiled for preaching.
What this jihad changed for Islam's spread reached beyond the caliphate's own borders. Sokoto's example and its networks helped inspire further jihad states in Senegal, Mali and Chad, making dan Fodio's uprising the most significant expansion of organised Islam in West Africa since the medieval Mali Empire, carried not by traders or missionaries but by a preacher turned into the founder of an empire.