If you search for the richest people who ever existed, some such lists will have one "Mansa Musa" at the top, some kind of king of western Africa from the 1300's. How rich was he? How much wealth did he have? We don't know. Nor do these lists tell how much it was. So how do we know he was the richest person who ever existed? We don't. He just is, because he is, period. Sure, we don't know how much wealth he had, but he's still the richest person who ever existed. Because. I'm not even kidding. Historians, and of course Wikipedia , have a very detailed account of his life and acts. These are recounted in great detail and with conviction, as if they were very well known and certain indisputable historical facts. These include the historical "fact" that he once traveled from western Africa across the Saharan desert all the way to Egypt with several tens of thousands of people and innumerable amount of gold, and freely distributed this gold there...