That being said, the question was asked and we aim to please, so this is our best attempt at a “richest person” list. 14th centuryMansa Musa I – Worth approximately $400 billionThe richest person in history wasn’t Bill Gates or John D. Rockefeller, but the 14th century ruler of West Africa’s Malian Empire (covering modern-day Ghana, Timbuktu, and Mali), Mansa Musa. 18th centuryStephen Girard – Worth approximately $105 billionThis was a tough century because several moguls amassed their wealth in the 18th century, but continued to accumulate into the 19th century. 20th centuryJohn D. Rockefeller – Worth approximately $340 billionAs the 19th century turned into the 20th century, the greatest commodity in the world wasn’t land or people or harems, but oil. 21st centuryMuammar Gaddafi – Worth approximately $200 billionWe are only 14 years into the century, but the richest person of the 21st century is considered to be about the eighth richest person in all of history, give or take.