So - after collecting additional ifos from the web - this is the `state of the artī now:
India, Bengal Sultanate, Nasir al-Din Nusrat Shah (925-938 AH; 1519-1531 AD), Dar al-Darb - Fathabad mint, AH 925 / 1519 AD.,
AR Tanka (26-27 mm / 10,57 g),
Obv. / Rev.: "Al-Sultan bin al-sultan Nasir al-Dunya wa'l din abu'l Muzaffar Nusratshah al-Sultan bin-Husein Shah al-Sultan al-huseini khallada allah mulkahu" (spread on both sides, mint and date spread over both sides, Fathabad on obverse, Darl-al-darb on reverse), 7 punchmarks / banker's marks on one side.
Goron and Goenka "The coins of the Indian Sultanates" B810 ; for punchmarks see
http://www.coincoin.com/I068.htm .
Nasiruddin Nasrat Shah, son of Sultan Alauddin Hussain Shah, was sultan of Bengal from 1519 until his assassination in 1531-2. (Hussain Shahi dynasty that ruled from 1494-1538). He continued his father's expansionist policies after succeeding him, adding more territory to his sultanate early on in his reign, but after 1526 had to contend with the Mughal ascendency, and also suffered a reverse at the hands of the Ahom kingdom.
Thanks to "engipress", "Oesho" and "Overlord" for their significant supporting of the id process.
Werner