The Dawoodi Bohra community traces its spiritual heritage from Prophet Mohammed and his Vasi Amirul Mumineen Moulana Ali, son-in-law of the Prophet, and continuing through their successors, the Imams, who, functioning first from Medina, spread over to North Africa and Egypt in the succeeding centuries. Imam Al-Mehdi Billah set out for North Africa and established his religious kingdom in Tunisia and the adjacent territories. Three Imams succeeded him and the fourth, the celebrated Imam Al-Moiz Le-dinillah, established his seat of authority in Egypt. Read more on the link above