Abu Abdullah al-Hussain bin Ahmad bin Muhammad bin Zakariya, commonly known as Abu Abdullah al-Shi'i was hailed from Kufa, where he had been an inspector of weights and measures, and was also an ascetic of Shiite inclinations, having been converted along with his brother, Abul Abbas bin Ahmad to Ismailism by dai Firuz. Realizing his potential, Imam Radi Abdullah had sent him to Ibn Hawshab in Yamen for further training in Ismaili esoteric doctrines as well as affairs of the state. Abu Abdullah stayed in Yamen with Ibn Hawshab for a year.
The Ismaili mission had its roots in the era of Imam Jafar Sadik. As early as the year 145/762, the two dais, called Halwani and Abu Sufiani had been dispatched to the Maghrib. They settled among the Berbers in the land of Katama and summoned the local populance to the cause of Ahl-al-Bait, and converted a bulk of people to their doctrines. Abu Sufiani died a few years later, but Halwani lived for a long time. Knowing the death of Halwani and Abu Sufiani in Maghrib, Ibn Athir (d. 630/1234) writes in "Kamil fi't Tarikh" (Beirut, 1975, 8th vol., p 31) that Ibn Hawshab told to Abu Abdullah: "Our missionaries have thoroughly ploughed the land of Maghrib, making it arable. None is capable except you after them. You prepare yourself now for Maghrib."
Abu Abdullah set out from Yamen in 279/892, accompanied by another dai Abdullah bin Abul Malahif. He arrived in Mecca during pilgrimage, where he contacted the Katama pilgrims of Maghrib lodging at Mina, and impressed them with his vast knowledge about the merits of Ahl- al-Bait. The pilgrims were gladdened to know that Abu Abdullah was heading towards Egypt, which was on their route to the Maghrib. While travelling with them, Abu Abdullah inquired at great length about their country in order to judge the suitability of his mission. He, thus gained the admiration of his fellow-travellers. After a short stay in Egypt, he reached Maghrib in the Katama homeland on 14th Rabi I, 280/June 3, 893.
The name maghrib (the land of sunset) was given by the Arabs to that virgin part of Africa, which European have called Barbery or Africa Minor, (the French Afrique du Nord), and then North Africa. In north it is bordered by the Mediterranean, and in the south by the Sahara desert. In the west it is extended as far as the Atlantic Ocean, and in the east it extends as far as the borders of Egypt. The jazirat al-maghrib i.e., "the island of the setting sun," consists of that part of the North Africa, which includes Morocco, Algeria, Tunisia, Cyrenaica, and Tripolitania.
The word Berber is derived from Latin barbari, an appellation equivalent to the English "barbarian", which the Romans used to call peoples who spoke neither Latin nor Greek. The social organisation of the Berbers or Katama Berbers had been tribal from the earliest known period of their history. Ibn Khaldun distinguished three major divisions among the Berbers, i.e., the Zanata, Sanhaja and Masmuda. The Zanata, whose original home was in Tripolitania and southern Tunisia, were predominately nomadic. The Sanhaja were as widely dispersed in the Maghrib as the Zanata. The Sanhaja were split into two main branches: the Kabylia Berbers, who were sedentary, and the nomadic Zanaga, whose traditional home had been the western Sahara desert. The Masmuda were the sedentary Berbers of Morocco. Hence, it must be known that the Katama Berbers had embraced Ismailism and took prominent part towards the foundation of the Fatimid Caliphate in Maghrib.
Abu Abdullah established his base in Ikjan (the Tzajjan of the Romans) near Satif, a mountain stronghold that dominated the pilgrimage route, where he spent seven years in propagating the cause of Ahl-al-Bait among the old people as well as the youths of the Berber tribes. Very soon the tribesmen in the vicinity began to trek to Ikjan. He completely swayed a large body of Berber tribesmen amongst whom the Katama tribe was very prominent and powerful. Abu Abdullah, however, had to face many vicissitudes, sometimes meeting with success and sometimes facing defeats, but he never wavered in his resolve.
In the interim, the report of the tremendous popularity of Abu Abdullah began to filter through to the Aghlabid ruler, Ibrahim bin Ahmad, who wrote to his governor of Meila to subdue Abu Abdullah, but of no avail. Meanwhile, Abu Abdullah, feeling full confident of his strength, began to wave of conquests. Ibrahim bin Ahmad dispatched a large army in 289/901 under his grandson, who made success to some extent. A number of Katama leaders, wary of Aghlabid inroads into their country, sought to banish Abu Abdullah and in the ensuing battle, he gained upper hand. Ibrahim bin Ahmad died in 291/903 and was succeeded by his son, Ziadatullah, a man indolent and entirely devoted to pleasure. Abu Abdullah captured Tahirt and his followers built living quarters around it. Immediately, he set on laying the foundations of administration for his principality and divided the Katama into seven units, each with its own army with wide powers. After consolidating his position in the Katama country, Abu Abdullahh embarked on his second phase of conquests. He advanced on Meila which surrendered after a brief resistance. He then marched on Satif. With the conquest of this city, Abu Abdullah openly declared the purpose of his mission that:- "I am propagating for God, the Almighty, the Exalted, for His Book and for Imam al-Mahdi from the progeny of the Apostle of God."
Abu Abdullah's success in overcoming the major internal opposition movements as well as conquering one territory after another at last awakened Ziadatullah from his slumber. He sent a large force to curb Abu Abdullah's power. The two armies met at Billizma. This new encounter resulted in two more cities, Billizma and Tubna, falling into the hands of Abu Abdullah.
Abu Abdullah was now feeling confident that the mission organisation as well as the basic framework of the state were clearly emerging with good result. He, therefore, deputed some prominent leaders of Katama tribe led by his brother, Abul Abbas in Salamia, and sent an invitation to al-Mahdi for Maghrib to take over the reigns of government.