Rare tanka, Tamerlane (1370-1405) w/overlord Mahmud, Herat, Timurids

Naskh legend: Shahada in a complex figure // Circle with Zarb Damghan and retrograde date 799 (=1316),  Naksh legends in the circular margin: Sultan Mahmud Khan Khallada Allah Mulkahu  Amir Timur Kurkan. 31mm, 5.85 grams. Damghan mint, 799 AH (1396). cf.Zeno 5708. 

Nice and rare large silver tanka, one year type. Possibly with a countermark on obverse (or maybe a double strike). A very nice example of a coin of one of the cruelest and infamous rulers of all times!