And some of the ismailites created Fatimid caliphate, ruled by people claiming to be descendants of Isma'il, thus of Muhammad, his daughter Fatima (hence the name), and Ali, her husband. Their country was created in what nowdays is Tunisia, but at some point they controled entire Northern Africa, Sicily, Palestine, Jordan, Hijaz, Lebanon, Syria. When they conquered Egypt, they moved their capital to a city they founded there: Cairo. They also established there the fameous Al-Azhar university.
Fatimid theology, like ismaili theology in general, became a bit "heretical" from sunni point of view. In result, they were quite tolerant to all religions and denominations. It was changed for some time under the said Al-Hakim, who persecuted sunnis, even more so non-muslims, and out of them christians in particular. The general view is that Al-Hakim was crazy, but my thesis aimed at finding the reasons why he persecuted christians, and why he stopped persecuting them shortly before his death.