The vizier (Arabic: وزير, romanized: wazīr) was the senior minister of the Fatimid Caliphate for most of the Egyptian period of its existence.
These "viziers of the sword" were also commanders-in-chief of the army who effectively sidelined the caliphs and ruled in their stead, often seizing power from their predecessors.
[3] Likewise, when Caliph al-Mu'izz li-Din Allah (r. 953–975) arrived in Egypt, he preferred to avoid delegating his powers to a vizier, although he appointed Ya'qub ibn Killis, a former Ikhshidid official, as head of the administrative apparatus.
It was only c. 979 that Caliph al-Aziz Billah (r. 975–996) gave the title of vizier to Ibn Killis, who continued as head of the administration until his death in 991.
[1][7] The "viziers of the sword", who dominated the last century of the Caliphate's existence, were at the same time chief ministers in charge of all civil administration, heads of the armies (amīr al-juyūsh), responsible for all judicial matters as chief qāḍī, and even for all religious matters as head missionary (dāʿī al-duʿāt).
[12] The building was not only the residence of the vizier, but also the seat of the fiscal bureaus (dīwāns), and housed storage rooms for garments, the treasury, books, and drinks.
[13] The dār al-wazāra was an echo of the caliphal palaces, and included a small mosque for prayer and kitchens for the banquets organized by the vizier.