Watch List notes:

ISLAMIC, 'Abbasid Caliphate. Al-Mahdi, AH 158-169 / AD 775-785. Dirham (Silver, 23.5 mm, 2.86 g, 3 h), citing the caliph al-Mahdi, al-Muhammadiya, AH 161 = AD 777/8. SICA III, 1347. Minor marks, otherwise, very fine.