Mansa Musa is said to be the richest man in all of history, making over $400 billion in his life time (according nytimes). Mansa Musa (1280-1337) was the king of the West African Malian Empire which also included Ghana. His wealth was as a result of his empire’s ability to produce more than half the world’s supply of salt and gold. Keep in mind that salt was a very very hot commodity back then.
As a devout Muslim, Mansa Musa made a pilgrimage to Mecca, taking with him over 60,000 delegates and 12,000 slaves, each carrying 4 lbs of gold and other merchandise. He was so rich that during his journey, he traded in gold for souvenirs and gave gold as a gift to everyone he met. So much so that he single-handedly caused an inflation in cities in Medina and Cairo (he traded in gold and gave the poor gold as gifts, so inflation occurred as the cities tried to readjust their economy in response to its new found wealth…cool eh?). He was also responsible for building mosque along the way on his famous journey to Mecca. Legend (and oral accounts) has it that he built a new mosque every Friday.
Although his wealth was eventually lost after his death, because his descendants couldn’t fend of invaders and what not, Mansa Musa’s wealth has yet to be matched. It’s worth noting that the persons that has come a close second to his wealth is the famous European banking dynasty, The Rothschild family, amassing about $350 billion - making them the 2nd richest in the history of the world as we know.