Tahirids, Tahir bin al-Husayn, rebel (AH 205-207 / AD 821-823). AR Dirham (27mm, 2.88g). Madinat Herat mint, AH 206 = AD 822. Kalima in three lines across field, citing al-Shukr bin Ibrahim; mint and date formula around / Continuation of kalima in three lines across field, citing Dhu'l-Yaminayn. A-1391A; Lowick 2243. Roughness on rev., otherwise Good VF