The richest man of all time was reportedly an African ruler, Mansa Musa I. His personals worth is estimated to be $400 billion at the time of his death in 1331, adjusted for inflation. Mansa Musa I ruled the Malian Empire, which today encompasses Ghana, Timbuktu and Mali.
His country’s production of more than half the world’s supply of salt and gold contributed to Musa’s vast wealth, which he used to build large mosques that still stand today.
According to the writings of Arab-Egyptian scholar Al-Umari, Musa inherited his throne through a practice of appointing a deputy after the king goes on his pilgrimage to Mecca; later naming the deputy as heir.
Musa was appointed deputy of the king before him, who had reportedly embarked on an expedition to explore the limits of the Atlantic ocean, and never returned.
Just two generations after his death, however, Musa’s world record net worth was diminished after is heirs were not able to fend off civil war and invading conquerors. Source