During the time of the fifth Imam, Mowlana Ja'far as-sadiq, the Kutama tribesmen had been visited by Dais Halwani and Sufiyani, and these Dais had died there. Other Ismaili Dais had also visited the place.
Therefore when Dai Abu Abdullah came there in 280 A.H., he found no difficulty in gaining the support of the local population for Imam al-Mahdi. The whole of North Africa, including its capital, Qairawan, was now conquered by the Kutama soldiers under the leadership of Dai Abu Abdullah, who then prepared to invade Sijilmasa and release the Imam from captivity.
The governor of Sijilmasa, on hearing about Dai Abu Abdullah's arrival, fled from there. The Dai entered the town, released all the prisoners, including the Imam whom he greeted with tears in his eyes. He took the Imam to his army and told them to pay their respects to the Imam, for he was their Lord.
After having established the Fatimid Caliphate at Raqqada, Imam al-Mahdi began to build his Empire. He brought the Island of Sicily under his control and founded new towns Mehdiya and Muhammadiya. All this was in preparation for his final move, the invasion of Egypt.
As soon as Imam al-Mahdi came to know of this, he had Dai Abu Abdullah and his brothers killed in 298 A.H. Imam knew that although in the later part of his career, Dai Abu Abdullah got misled, in his earlier days, he had served the Imam well with love and loyalty. Therefore, the Imam decided to give the Dai a public burial, thus honouring him with gratitude.
During his father's life time, Imam al-Qaim subdued various Berber and Kharajide uprisings. He carried out two invasions on Egypt, which unfortunately had to be withdrawn.
During Imam al-Qaim's time, Abu Yazid conquered many important towns, including Baja, Raqqada and Qairawan. Imam al-Qaim sought refuge in Mehdiya, at which Abu Yazid laid a siege in 334 A.H. Due to the high morale which the Imam inspired and due to the large reserves of food, which were wisely stocked in the town in advance, the Fatimid capital was able to outlive the siege and tireout the besiegers, who under Abu Yazid, withdrew to Susa.
During Imam al-Mansoor's time, Abu Yazid continued to make trouble and Imam laid a seige at Susa. A battle was fought in which Imam al-Mansoor himself took part. The Imam defeated Abu Yazid and drew him away to Morocco. However, Abu Yazid continued to harass Imam's forces. He was finally defeated at Fort Kutama, where he was seriously wounded. He died soon after in a prison in 336 A.H.
Imam al-Mansoor respected the memory of Abu Yazid as he was a brave enemy and looked after all his family. Qadhi Nauman, the chief Fatimid Judge and author in the service of the first four Fatimid Caliphs, wrote an entire book on Abu Yazid; the book, however, has been lost. Besides Abu Yazid's revolt, Imam al-Mansoor had to face another revolt, but he was finally able to supress this revolt in 336 A.H.
Abdullah, the son of Maymun al-Qaddah, had served Imam Muhammad bin Ismail as his chief advisor and Dai throughout his life. After the death of Imam Muhammad bin Ismail, he continued to be the advisor of Imam Wafi Ahmad. He became Imam's "Hujja" (chief Dai), as well as his"Hidjab" (cover).