Yamen was the original base of the Fatimid propaganda, where Ibn Hawshab had formed an Ismaili state in 268/882. Long after his death, the political power slipped away from the hands of the Ismailis, but their mission continued actively. During the period of az-Zahir, the headship of the Yamenite mission had come to be vested in a certain dai Suleman bin Abdullah al-Zawahi, a learned and influential person residing in the mountainous region of Haraz. He made a large conversion and wished to re-establish the political power of the Ismailis in Yamen. It is said that a certain Hamdani chieftain, named Ali bin Muhammad al-Sulayhi, the son of the qadi of Haraz, once came to lead the pilgrim caravans to Mecca, and had learnt much about Ismaili doctrines from Suleman and espoused Ismailism. Ali took a leading part in the mission works in Yamen and became the assistant of Suleman, who chose him as his successor. Ali bin Muhammad al-Sulayhi generated his close contact with az-Zahir and the mission headquarters in Cairo.
In 429/1038, during the period of Imam al-Mustansir billah, Ali bin Muhammad captured Mount Masar in Haraz to the north of Yamen, and fortified it, whom he made his centre. This marked the foundation of the Sulayhid dynasty, which ruled over Yamen as a vassal of the Fatimids for almost a century until 532/1138. He obtained support from the Hamdani, Humayri and other petty tribes of Yamen and instituted the Fatimid khutba everywhere. His further detail will run hereinafter.
We have discussed previously that Fatik, the governor of Aleppo had declared himself as an independent ruler on the eve of the death of Imam al-Hakim. Later on, Fatik admitted his mistakes and apologized from az-Zahir and Sit al-Mulk. In 413/1022, Badr, the commander of the stronghold of Aleppo had killed Fatik. In the following year, az-Zahir expelled Badr from Aleppo and appointed Abdullah bin Ali bin Jafar al-Katami as the governor of Aleppo and Safi ad-Dawla to administer the command of the stronghold.
During the later part of az-Zahir's rule, the Fatimid influence had become supreme in Palestine and Syria, save only in the few northern districts which remained subject to the Greek empire. It seemed indeed to be the triumph of the Fatimids.
Ali bin Suleman was a pioneer physician, philosopher, mathematician and an astronomer, who died during the early part of the Imamate of az- Zahir. Unfortunately, his works are lost; these included two important compendiums mentioned by their titles in the literature: a synopsis of "Kitab al-Hawi fi'l Tibb" by Abu Bakr Muhammad bin Zakaria ar-Razi (d. 313/925) of Iran, and a book on professional aphorism, ethics, experiences, anecdotes and properties of natural products compiled from the writing of the ancient sages. Ibn Abi Usaibia (d. 668/1270) explains in "Uyun al-Anba fi tabakat al-Attiba" (2nd vol., pp. 89-90) that he had seen a copy of this latter work in four volumes, wherein the author mentioned that he started this compilation at Cairo in 391/1000.
In Cairo, Abu Sa'ad Ibrahim (d. 440/1048) was a famous Jewish dealer in very rare and precious things and made long journey to acquire them. Imam az-Zahir used to be a frequent customer of Abu Sa'ad, from whom he bought antiques for his personal collections.
It should be remembered that the Fatimids made great contribution in the rock-crystal works in various forms, mostly developed during the time of Imam az-Zahir, such as ewers, bottles, cups, saucers, boxes, chessmen and flasks of different shapes. One of these interesting piece is preserved in crescent shape work in the Germanisches National Museum in Nurnberg. It was originally used as an ornament for one of the horses of az-Zahir, whose name is inscribed on it. There are also another rock-crystal mugs in the collections of Lourvre, Venice, Vienna and Prague; belonging to the period of Imam az-Zahir.
The period under review is also noted for an Ismaili scientist, Abu Ali Ibn Sina, whose biography has been given in Appendix II.
It must be remembered on that juncture that it was az-Zahir who, in 421/1030 and again in 424/1033 rebuilt the walls of Jerusalem which had collapsed following an earthquake. He was also responsible for rebuilding the Aqsa Mosque and the repair of its mosaics.
In 427/1036, az-Zahir was detained some time by sickness. He was taken to Maks, then the port of Cairo, where he died on the 15th of Shaban, 427/June 13, 1036, leaving the Caliphate and Imamate to his son, al-Mustansir, then a child of seven years of age.