Watch List notes:

ISLAMIC, 'Abbasid Caliphate. temp. Al-Mahdi, AH 158-169 / AD 775-785. Dirham (Silver, 24 mm, 2.72 g, 7 h), citing al-Mahdi as 'al-Khalifa', al-Basra, AH 160 = AD 776/7. SICA III, 595. Nicely toned. Minor scratch on the obverse, otherwise, about extremely fine.