Which West African empire's ruler crashed Egypt's gold price on a single pilgrimage?

Mali, under Mansa Musa, who crossed to Mecca in 1324 with a caravan reported in thousands and gave away and spent so much gold in Cairo that its value there was still depressed a decade later. It is the only case anyone cites of a single traveller moving a regional economy by accident.

The wealth was structural rather than personal. Mali sat on the routes carrying West African gold north and Saharan salt south, and taxed both; salt traded near its weight in gold in the forest zone, where the body needs it and the ground has none. On the way home he recruited an Andalusian architect, and the mud-brick monumental style of Timbuktu and Djenné follows from it.

The pilgrimage put Mali on European maps. The Catalan Atlas of 1375 shows him seated with a gold nugget and a crown, which is how a West African emperor became a fixture of medieval European geography. Modern lists calling him the richest person in history are not meaningful - there is no way to price a fourteenth-century empire against a modern fortune - but the contemporary accounts of the Cairo gold market are real.