ʿAlī ibn al-Faḍl al-Jayshānī () was a senior Isma'ili missionary () from Yemen. In cooperation with Ibn Hawshab, he established the Isma'ili creed in his home country and conquered much of it in the 890s and 900s in the name of the hidden Isma'ili imam, Abdallah al-Mahdi Billah. After the establishment of the Fatimid Caliphate in Ifriqiya in 909, and the public proclamation of al-Mahdi Billah as caliph, Ibn al-Fadl denounced al-Mahdi as false, and instead declared himself to be the awaited messiah (). His erstwhile colleague, Ibn Hawshab, refused to follow him, so Ibn al-Fadl turned against him and forced him to capitulate. Ibn al-Fadl's dominion collapsed swiftly after his death in October 915. In January 917, his stronghold of Mudhaykhira was seized by the Yu'firids, his children captured, and his two sons executed. Origin Ali ibn al-Fadl was born in the village of Suhayb, near the town of Jayshan (today ruined, near modern ), in southern Yemen. A member of the Sabaean tribe, he was a Shi'ite. With others of his tribe, he went on the pilgrimage to Mecca in 880, and then continued north to visit the Shi'a shrine of Karbala in Iraq. It was there that his fervent devotion before al-Husayn's tomb was remarked upon by an Isma'ili agent (), leading to his recruitment to the Isma'ili cause. At the time, the dominant strain of Twelver Shi'ism was in a crisis. The disappearance of their eleventh imam, Hasan al-Askari, in 874, apparently without male progeny, had raised doubts, and many Shi'a were further demoralized by the political impotence and quietism of the Twelver leadership against the Abbasid Caliphate. In this climate, many dissatisfied Twelvers were drawn to the millennialism of the rival Isma'ili branch, who preached the imminent return of the , the messianic figure of Islamic eschatology, who according to legend would overthrow the usurping Abbasids and destroy their capital Baghdad, restore the unity of the Muslims, conquer Constantinople, ensure the final triumph of Islam and establish a reign of peace and justice. Mission to Yemen Ibn al-Fadl's conversion opened the prospect of extending the secret Isma'ili missionary mission () to Yemen. For this purpose, Ibn al-Fadl was teamed up with an older convert, the Kufan Ibn Hawshab. Setting off in late May or early June 881, the two men made for Kufa, where they joined the pilgrim caravans, whose multitudes, gathered from all corners