Watch List notes:

ABBASID: al-Ma'mun, 810-833, AR dirham (2.64g), al-Muhammadiya, AH202, A-224, Very Fine, R. 'Ali b. Musa al-Rida, Imam of the Shi'ite faction, was named heir to the caliphate as part of a failed attempt to reconcile the Sunni and Shi'ite branches of Islam.

Estimate: 500-600 USD