RARE! Bengal issue tanka of Balban (1266-1287), Lakhnauti mint in Bengal, Delhi

Description

Legend spread on both sides: Al Sultan al-azam ghiyath al-dunya wa'l din abu'l sutan muzaffar / al Imam al-Mustasim amir al-muminin ("Imam al-Mustasim, leader of the faithful), date and mint in circular margins. Superb high quality, light toning. Dated to 667 AH = 1268 AD. 29mm, 10.7 grams. Mint of Lakhnauti. Very rare!!! "The Coins of the Indian Sultanates" B78, Rajgor 936.
Might be of type B-79 (with the month of the issue written along with the year), but the month is not visible (struck off-flan?).
On Oct 5, 2022 at 08:12:34 PDT, seller added the following information: