Great Council of Venice
In the 13th century, the Venetians imported goods from the East and sold them at a profit north of the Alps. They paid for these goods with Byzantine gold coins but when the Byzantine emperor Michael VIII Palaiologos backed a rebellion called the Sicilian Vespers in 1282, he debased the hyperpyron. This was just one more in a series of debasements of the hyperpyron and the Great Council of Venice responded with its own coin of pure gold in 1284.