Imam Abdullah al Mahdi Billah SA is the eleventh Imam after his father, Imam Husain al Zaki SA. His kuniyat is “Abi Mohammed,” the father of Mohammed.
Imam Husain al Zaki SA hailed the zuhoor of Imam al Mahdi SA and persevered to lay the foundations of his dawat even as he prepared to found the zahiri mamlakat (kingdom) of Aimmat Tahereen SA. After the passing away of his father, Imam al Mahdi SA set forth on a journey to the West from whence he launched a campaign to conquer the region of North Africa from al Maghreb to Egypt and establish the Fatemi kingdom.
The Imam SA resided in Salamiyah until the armies of the Qarmatines, a faction who had forsaken Islam, and that of the Baghdadi Caliph Al Mo’tadid encroached upon him. The Imam SA left Salamiyah before either could succeed in their evil plan. Imam al Mahdi SA and Imam Mohammed al Qa’im SA traveled westwards with a company of faithful followers, even as it was being maintained that the Imam was journeying East to Yemen.
Meanwhile, the armies of the Qarmatines invaded Salamiyah and ransacked the palace of the Imam. They were encountered by the Baghdadi horde and captured. The Qarmatine leader revealed the description of the Imam to his captors, which was quickly sent to every Abbasid principality, with the order that the man fitting the given description be captured immediately.
The Imam SA reached the city of Ramlah, where the dispatch of his capture had arrived, but the governor of the city was a faithful follower; he sent back to Baghdad that although they were on a vigilant look out, no such man had come through the city. The Imam SA and his entourage safely passed through Ramlah, and continued their journey to the West.
The Imam finally arrived at the city of Sijilmasah. One day, as the Imam SA and Imam al Qa’im SA came out into the garden adjoining their house. The Imam SA sat under a tree while Imam al Qa’im SA took a stroll, and came by a pond, in which he washed his hands, and dipped his feet. The pond overflowed, and the gardener, on seeing this miracle, exclaimed: “By Allah, this is the Mahdi.” He was brought before the Imam SA who questioned him how he knew about the Mahdi. The gardener answered that he had heard his father and grandfather talk of a day when a man would dip his feet in this pond and it would run over, and that this man would be al Mahdi or his son.
Imam al Mahdi SA remained in Sijilmasah for 40 days and then left for Ifriqiyah (West Africa). The dawlat of al Mahdi rose from al Maghrib after 300 years as Rasulullah SAW had foretold.
The city of Al Mahdiyyah was built. It was constructed from iron and stone, and made impenetrable. The Imam relocated to the new city in 308 H, and resided there until the year of his passing away in 322 H. He reigned over the newly formed Fatimi kingdom for 36 years.