Watch List notes:

ISLAMIC COINS, ABBASID CALIPHATE, al-Ma'mun, Silver Dirham, Samarqand 203h citing the Shite Iman 'Ali b. Musa al-Rida as heir, 2.86g (A 224). Good very fine, toned and rare.
This issue by the Caliph al-Ma'mun was an attempt to unify Sunni and Shite Islam

Estimate: £400-500