Early Medieval & Islamic ISLAMIC, 'Abbasid Caliphate. temp. Al-Mahdi, AH 158-169 / AD 775-785. Hemidrach 2,70gr 26,99mm, citing governor ʿUmar ibn al-ʿAlā (PYE 120-129 = AH 155-164 = AD 771-780), Tabaristan Draped Sasanian-style bust to right,