then rapidly overthrow the usurping Abbasid Caliphate 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. For the Isma'ilis, that was Muhammad ibn Isma'il, the seventh imam in a line stretching from Ali ibn Abi Talib, the son-in-law of the Islamic prophet Muhammad. While the remained hidden, he was represented by an agent, living proof of the imam's existence, the (). That was the role claimed by Abdallah al-Akbar, and he was in turn succeeded in 827/8 by his son Ahmad, followed by Abu'l-Shalaghlagh. Abu'l-Shalaghlagh did not have heirs, as his son and grandchild had reportedly been captured and imprisoned by the Abbasids. Sa'id was thus designated as his successor, and given his uncle's daughter in marriage. Sa'id's only child, Abd al-Rahman, the future caliph al-Qa'im bi-Amr Allah, was born in March or April 893. His brother, Abu Muhammad, apparently went to Taleqan in the Daylam, a region where already Abdallah al-Akbar had lived and preached for a while. Leadership of the Isma'ili and the Qarmatian schism While the heads of the Isma'ili remained hidden in Salamiya, known only to the chief s of each region, their organization was growing. During the late 9th century, millennialist expectations increased in the Muslim world, coinciding with a deep crisis of the Abbasid Caliphate during the decade-long Anarchy at Samarra, the rise of breakaway and autonomous regimes in the provinces, and the large-scale Zanj Rebellion, whose leader claimed Alid descent and proclaimed himself as the . In this chaotic atmosphere, and with the Abbasids preoccupied with suppressing the Zanj uprising, the Isma'ili found fertile ground, aided by dissatisfaction among the adherents of the rival Twelver branch of Shi'a Islam with the political quietism of their leadership and the recent disappearance of their own imam. s like Hamdan Qarmat and his brother-in-law Abdan spread their network of agents to the area around Kufa in the late 870s, and from there to Yemen (Ibn Hawshab, 882) and thence India (884), Bahrayn (Abu Sa'id al-Jannabi, 899), Persia, and Ifriqiya (Abu Abdallah al-Shi'i, 893). The true head of the movement remained hidden even from the senior missionaries, however, and a certain Fayruz functioned as chief missionary () and 'gateway' () to the hidden leader. While ostensibly merely the stewards for the hidden imam, the eunuch Ja'far reports that Abu'l-Shalaghlagh—perhaps