Excerpts from Books and Wikipedia
"The Fatimids emerge in North Africa in the early 10th century, directly challenging centralized Abbasid authority. In 969 their general Jawhar conquered a force of 10,000 men and built a new city north of the ancient settlement of Fustat, encircled by fortified walls and containing palaces, great mosques, and plazas. They called their new city al-Qahira, 'The Victorious,' a name later corrupted by European tongues to 'Cairo.'
Under the caliph al-Aziz (975-996), Egypt became the richest and most stable region in the Islamic world, and the heart of a revived Eurasian trading network. The zenith of Fatimid power was reached during the caliphate of al Mustansir (1036-94), although high taxation and unrest led to a half-century of steady decline." [DK Timelines, p. 151]