ISLAMIC, 'Abbasid Caliphate. temp. Al-Mahdi, AH 158-169 / AD 775-785. Hemidrachm (Silver, 23 mm, 2.00 g, 9 h), Arab-Sasanian type, citing governor Yahya ibn Mikhnaq (PYE 128-130 = AH 163-165 = AD 779-781), Tabaristan, PYE 129 = AH 164 = AD 780. Draped Sasanian-style bust to right, wearing an elaborate crown; behind head, ‘GDE / ʾp̄zwt’ (‘[may his] glory increase’ in Pahlavi); before head, ‘Yaḥyā’ (‘Yahya’ in Arabic); in outer margin to left and right, ‘nywk' ˗ ʾp̄d’ (‘good ˗ wonderful’ in Pahlavi). Rev. Fire altar, flanked by two attendants; above altar, star and crescent; to left, date in Pahlavi; to right, ‘tpwlstʾn’ (‘Tabaristan’ in Pahlavi). Album 60. Very rare. Minor deposits on the reverse, otherwise, good very fine.