Extremely rare silver tanka of Nasir Al-Din Mahmud (837-864 AH / 1433-1459), Bengal. Large silver coin, measuring 25mm, 10.9 grams. Inscriptions on both sides. Khalifatabad mint, dated to 847 AH / 1443 AD. Very attractive and large. Extremely rare type! "The coins of Indian Sultanates" #B417.