Watch List notes:

ISLAMIC, 'Abbasid Caliphate. temp. Al-Mahdi, AH 158-169 / AD 775-785. Dirham (Silver, 24.5 mm, 2.93 g, 12 h), citing al-Mahdi as 'al-Khalifa', Madinat al-Salam, AH 162 = AD 778/9. SICA III, 1628. Extremely fine.