Persia (Post-Mongol). Aq Qoyunlu. 'Ali, AH 839-841 / AD 1435-1438. 1/3 Tanka (Silver, 14 mm, 1.76 g, 11 h), Bayburt, AH 840 = AD 1436/7. Within a square, ‘lā ilāha illā / Allāh Muḥammad / rasūl Allāh’ (‘There is no deity but Allah. Muhammad is the messenger of Allah’ in Arabic); the names of the four Rashidun Caliphs in Arabic in the four surrounding panels: ‘Abūbakr / ʿUmar / ʿUthmān / ʿAlī’. Rev. Within a central circle, ‘ḍarb / Bāyburt / sana 840’ (‘Struck in Bayburt, year 840’ in Arabic); deteriorated legend in the margin, including ‘ʿAlī ibn ʿUthmān’ (‘ʿAli son of ʿUthman’ in Arabic). Album -. Zeno 304959. Extremely rare. Flan fault on the edge, otherwise, good very fine.