The Fāṭimids established a new and glorious city, Al-Qāhirah (“The Victorious”; Cairo), to rival ʿAbbāsid Baghdad. They then adopted the title of caliph, laying claim to be the legitimate rulers of all Muslims as well as head of all Ismāʿīlīs. Now three caliphs reigned in Islamdom, where there was supposed to be only one. In Cairo the Fāṭimids founded a great mosque-school complex, Al-Azhar. They fostered local handicraft production and revitalized the Red Sea route from India to the Mediterranean. They built up a navy to trade as well as to challenge the Byzantines and underscore the ʿAbbāsid caliph’s failure to defend and extend the frontiers. Fāṭimid occupation of the holy cities of Mecca and Medina, complete by the end of the 10th century, had economic as well as spiritual significance: it reinforced the caliph’s claim to leadership of all Muslims, provided wealth, and helped him keep watch on the west Arabian coast, from the Hejaz to the Yemen, where a sympathetic Zaydī Shīʿite dynasty had ruled since 897. Fāṭimid presence in the Indian Ocean was even strong enough to establish an Ismāʿīlī missionary in Sind. The Fāṭimids patronized the arts; Fāṭimid glass and ceramics were some of Islamdom’s most brilliant. As in other regions, imported styles and tastes were transformed by or supplemented with local artistic impulses, especially in architecture, the most characteristic form of Islamicate art.

The reign of one of the most unusual Fāṭimid caliphs, al-Ḥākim, from 996 to 1021, again demonstrated the interregional character of the Ismāʿīlī movement. Historians describe al-Ḥākim’s personal habits as eccentric, mercurial, and unpredictable to the point of cruelty and his religious values as inconsistent with official Ismāʿīlī teachings, tending toward some kind of accommodation with the Jamāʿī-Sunni majority. After he vanished under mysterious circumstances, his religious revisionism was not pursued by his successors or by the Ismāʿīlī establishment in Egypt, but in Syria it inspired a peasant revolt that produced the Druze, who still await al-Ḥākim’s return.

When the Fāṭimids expanded into southern Syria, another Shīʿite dynasty, the Ḥamdānids, of Bedouin origin, had been ruling northern Syria from Mosul since 905. In 944 a branch of the family had taken Aleppo; under the leadership of their most famous member, Sayf al-Dawlah (ruled c. 943–967), the Ḥamdānids responded aggressively to renewed Byzantine expansionism in eastern Anatolia. They ruled from Aleppo until they were absorbed by the Fāṭimids after 1004; at their court some of Islamdom’s most lastingly illustrious writers found patronage. Two notable examples are the poet al-Mutanabbī (915–965), who illustrated the importance of the poet as a premodern press agent of the court, and al-Fārābī, who tried to reconcile reason and revelation.

Al-Fārābī contributed to the ongoing Islamization of Hellenistic thought. Falsafah, the Arabic cognate for the Greek philosophia, included metaphysics and logic, as well as the positive sciences, such as mathematics, music, astronomy, and anatomy. Faylasūfs often earned their living as physicians, astrologers, or musicians. The faylasūf’s whole way of life, like that of the adīb, reflected his studies. It was often competitive with that of more self-consciously observant Muslims because the faylasūf often questioned the relationship of revelation to real truth. The faylasūfs felt free to explore inner truths not exposed to the view of ordinary people; they practiced prudent concealment (taqiyyah) of their deeper awareness wherever making it public might endanger the social order. The faylasūfs shared the principle of concealment with the Shīʿites; both believed, for rather different reasons, that inner truth was accessible to only a very few. This esotericism had counterparts in all premodern societies, where learning and literacy were severely restricted.