Mubarak Shah I (reigned 1317-21) ascended the throne of Delhi at the age of eighteen, having blinded the previous sultan, his brother Umar, a child of about six years old. His reign was short-lived and also ended violently when he was murdered by his favourite, Khusra Khan. The Muslim sultans of Delhi retained the ancient Indian tradition of minting square coins and also the use of Indian denominations, such as the tanka shown here. The Arabic legends however describe the sultan in traditional Islamic terms as 'the leader of the faithful' and 'the successor' of the Prophet Muhammad. Unusually, we know who minted this coin. It was minted by Thakkura Pheru, a Jain mint master for three sultans of Delhi. We know this, not because his name appears in the legend, but because his treatise on coinage, Dravya Pariksha ('Examination of coins'), was written in 1318, the same year as the coin was minted. In the medieval period, the Jains took on the role of India's bankers, and by this time, the Delhi sultans relied on their Jain bankers to organise army pay in remote regions.