Abbasid: al-Ma'mun (810-833), silver dirham (2.56g), Isbahan (Isfahan) mint, AH 202 (817-818 CE). Citing 'Ali ibn Musa al-Rida. Citing vizier Dhu'l-Ri'asatayn. Rare and elusive type.

Abbasid: al-Ma'mun (810-833), silver dirham (2.56g), Isbahan (Isfahan) mint, AH 202 (817-818 CE). Citing 'Ali ibn Musa al-Rida with titles "al-amir" (commander) and "wali 'ahd al-muslimin" (heir of the Muslims), and his full name 'Ali ibn Musa ibn 'Ali ibn Abi Talib. Citing vizier Dhu'l-Ri'asatayn. Phrase "al-mashriq" (The East) in obverse field. First year of issue for type. Album 224 (R). Brittle. Otherwise an exceptional, attractive condition for type. About uncirculated. Rare and elusive type. This extraordinary silver dirham marks al-Ma'mun's historic bid to unify the Muslim world by appointing 'Ali ibn Musa al-Rida, a revered scholar, jurist, and esteemed member of the Prophet's family (Ahl al-Bayt), as his official heir. Struck across major eastern mints with the notable Quranic passage from Surah ar-Rum (30:3-4) and the title of the vizier Dhu'l-Ri'asatayn, this issue captures an important element of Abbasid statecraft. While al-Rida was embraced during his lifetime by mainstream Muslim orthodoxy for his immense piety, noble lineage, and mastery of religious sciences, he would later come to hold a defining place in Shi'ite tradition as their Eighth Imam.