Isma'ili in the context of "Abu Abdallah al-Shi'i"

Abū Muḥammad ʿAbd Allāh ibn al-Ḥusayn (Arabic: أبو محمد عبد الله بن الحسين; 31 July 874 – 4 March 934), better known by his regnal name al-Mahdī biʾllāh (Arabic: المهدي بالله, "The Rightly Guided by God"), was the founder of the Isma'ili Fatimid Caliphate, the only major Shi'a caliphate in Islamic history, and the eleventh Imam of the Isma'ili branch of Shi'ism.

He was born as Saʿīd ibn al-Ḥusayn (سعيد بن الحسين) in Askar Mukram to a family that led the secret Isma'ili missionary network (da'wa), propagating on behalf of the hidden imam, Muhammad ibn Isma'il, who would return as the prophesied Islamic messiah (mahdi). Orphaned at a young age, he moved to Salamiya, the family's base of operations, where he was adopted by his uncle. In the mid-890s Sa'id succeeded to the leadership of the expanding da'wa, which had expanded and gained adherents across the then Muslim world. However, his claims of not merely being a trustee of the hidden imam, but of him and his ancestors holding the imamate itself, led in 899 to a schism in the Isma'ili movement: those who did not recognise his claims split off to become the Qarmatians. The schism was followed by uprisings of pro-Isma'ili Bedouin in Syria in 902–903, launched without his consent by over-eager supporters, who aimed to force him to come forward as the mahdi. The Bedouin uprising was suppressed by the Abbasids, but drew the attention of the Abbasid Caliphate's authorities to him, forcing him to abandon Salamiya, and flee first to Ramla, then Fustat in Egypt, and finally Sijilmasa in what is now Morocco. There he remained, living as a merchant, until one of his missionaries, Abu Abdallah al-Shi'i, at the head of the Kutama Berbers overthrew the Aghlabid dynasty of Ifriqiya in 909.

Nass (Arabic: نَصّ, romanized: naṣṣ) is an Arabic word variously translated as "a known, clear legal injunction," a "divine decree", a "designation", "written law" as opposed to unwritten law, "canonical text" that forbids or requires,a "textual proof".

In Shia Islam (Twelver and Isma'ili), nass refers specifically to the designation of an infallible Imam by a previous infallible Imam.

Idris Imad al-Din ibn al-Hasan al-Qurashi (Arabic: إدريس عماد الدين بن الحسن القرشي, romanized: ʾIdrīs ʿImād al-Dīn ibn al-Ḥasan al-Qurashī; 1392 – 10 June 1468) was the 19th Da'i al-Mutlaq of Tayyibi Isma'ilis from 1428 to 1468. A major religious and political leader in 15th-century Yemen, as well as a notable theologian, Idris was also an important medieval Isma'ili historian whose work is fundamental for the history of the Fatimid Caliphate and the Isma'ili communities in Yemen.

Satr (Arabic: ستر, lit. 'concealment') is a term used by the Isma'ili Shi'a for various periods in their history where the true imam was hidden (mastur) and represented through agents. These periods of concealment (dawr al-satr) might end with the renewed public manifestation of the imam, or continue until the present day. Entering into concealment did not mean that the line of imams stopped with the hidden imam; the Isma'ili concept is thus different from the concept of occultation (ghayba) as conceived by the Twelver Shi'a.

The Battle of Hama was fought some 24 km (15 mi) from the city of Hama in Syria on 29 November 903 between the forces of the Abbasid Caliphate and pro-Isma'ili Bedouin (called "Fatimids" or "Qarmatians"). The Abbasids were victorious, resulting in the capture and execution of the Isma'ili leadership. This removed the Isma'ili presence in northern Syria, and was followed by the suppression of another revolt in Iraq in 906. More importantly, it paved the way for the Abbasid attack on the autonomous Tulunid dynasty and the reincorporation of the Tulunid domains in southern Syria and Egypt into the Abbasid Caliphate.

Ja'far ibn Mansur al-Yaman (Arabic: جعفر بن منصور اليمن) was an Isma'ili missionary (dāʿī) and theological writer of the 10th century. Originally born and raised in Yemen, where his father Ibn Hawshab had established the Isma'ili daʿwa in the late 9th century, he fled the country to the court of the Fatimid caliphs in Ifriqiya, where he remained until his death. He composed poems in praise of the Fatimids' victory over the uprising of Abu Yazid, a biography of his father, and authored or compiled a number of important theological treatises.