Watch List notes:

ISLAMIC, 'Abbasid Caliphate. Al-Mahdi, AH 158-169 / AD 775-785. Dirham (Silver, 24.5 mm, 2.93 g, 6 h), with the califs name as "al-Khalifa al-Mahdi", Madinat al-Salam mint (Bagdad), 161 AH = 777/8. Album 215.1. SICA III, 1622. carefully struck and very attractively toned. Extremely fine.
From a collection in the USA.