Pre-reform issues, Tabaristan ('Abbasid governors). Yahya b. Mikhnaq. AH 163-165 / AD 779-781. AR Hemidrachm (22.9mm, 2.01 g, 6h). TPWRSTAN (Tabaristan) mint. Dated PYE 129 = AH 164 (AD 780/1). Name of governor before bust / Pellet above second 'T' of mint-name; star to left and crescent to right of flames. Malek 89.2; Album 60. AU.