Dan Fodio's son, Muhammed Bello, established the empire's capital in Sokoto and it has remained the centre of Nigerian Islam ever since, with its huge mosque opposite the sultan's palace.
BBC: The Sultan of Sokoto Mohammadu Maccido
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The new sultan will be chosen from Sokoto's ruling dynasty - descendents of Uthman Dan Fodio, who launched a jihad, or holy war, in 1804, spreading Islam across northern Nigeria and its neighbours.
BBC: The Sultan of Sokoto Mohammadu Maccido
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Dan Fodio, an ethnic Fulani Islamic scholar, rose up against the Hausa rulers of what is now northern Nigeria and Niger and created an empire which stretched from modern-day Burkina Faso to Cameroon, becoming one of Africa's largest pre-colonial states.