The history of aluminium was shaped by the usage of its compound alum. The first written record of alum was in the 5th century BCE by Greek historian Herodotus. The ancients used it as a dyeing mordant, in medicine, in chemical milling, and as a fire-resistant coating for wood to protect fortresses from enemy arson. Aluminium metal was unknown. Roman writer Petronius mentioned in his novel Satyricon that an unusual glass had been presented to the emperor: after it was thrown on the pavement, it did not break but only deformed. It was returned to its former shape using a hammer. After learning from the inventor that nobody else knew how to produce this material, the emperor had the inventor executed so that it did not diminish the price of gold. Variations of this story were mentioned briefly in Natural History by Roman historian Pliny the Elder (who noted the story had "been current through frequent repetition rather than authentic") and Roman History by Roman historian Cassius Dio. Some sources suggest this glass could be aluminium. It is possible aluminium-containing alloys were produced in China during the reign of the first Jin dynasty (266–420).
After the Crusades, alum was a commodity of international commerce; it was indispensable in the European fabric industry. Small alum mines were worked in Catholic Europe but most alum came from the Middle East. Alum continued to be traded through the Mediterranean Sea until the mid-15th century, when the Ottomans greatly increased export taxes. In a few years, alum was discovered in great abundance in Italy. Pope Pius II forbade all imports from the east, using the profits from the alum trade to start a war with the Ottomans. This newly found alum long played an important role in European pharmacy, but the high prices set by the papal government eventually made other states start their own production; large-scale alum mining came to other regions of Europe in the 16th century.