Muhammad bin Tughluq's token currency

The surviving coins of the new issue are dated from 730 to 732 AH — from late 1329 to the autumn of 1332 — and the contemporary poet-historian Isami says they circulated for three years. By the sultan's decree these base-metal pieces were to pass as the silver tanka. Barani blamed the measure on a treasury emptied by the sultan's lavish gifts and by his dream of conquering the world; Peter Jackson links it with the pay of the huge army raised for a planned invasion of Khurasan and with a shortage of silver that strained the whole monetary system, and the History and Culture of the Indian People thinks the idea was probably borrowed from the paper money then used in China and Persia.

The scheme failed because nothing distinguished the royal coins from imitations. In Barani's words, the edict "turned the house of every Hindu into a mint": forged tokens poured into circulation, the countryside paid its taxes in them, distant lands would take them only as copper, and they fell until they were "not valued more than pebbles or potsherds" (transl. H. M. Elliot and J. Dowson). The sultan revoked his edict and ordered the tokens to be brought to the treasury and exchanged for gold and silver coins; Barani says that heaps of them rose at Tughluqabad "like mountains". Jackson notes that this redemption itself shows the treasury was not as empty as Barani claimed.

By the time Ibn Battuta reached Delhi in 1334 the tokens had been withdrawn, and he does not mention them. Barani counted the copper money among the projects that ruined the sultan; some modern historians have judged it more kindly, as a measure undone by its execution rather than by its idea.