https://en.wikipedia.org/wiki/Mansa_Musa
Because of his nature of giving, Musa's massive spending and generous donations created a massive ten year gold recession. In the cities of Cairo, Medina, and Mecca, the sudden influx of gold devalued the metal significantly. Prices of goods and wares became greatly inflated. This mistake became apparent to Musa and on his way back from Mecca, he borrowed all of the gold he could carry from money-lenders in Cairo at high interest. This is the only time recorded in history that one man directly controlled the price of gold in the Mediterranean.