I don't know any history books. But from what I know and what is I'm 100% sure, Mansa Musa wasn't the greatest man to ever live, he is just regarded as the 'Richest man' to have ever lived, and richness doesn't imply greatness. The greates men to ever live are Alexander The Great and Napoleon Bonaparte. Other influencial men are Isaac Newton, Jesus Christ, Prophet Mohammed, Socrates, Plato, Aristotle, Rene Descartes, Immanuel Kant, and there are some others too. And I personally like to say Adolf Hitler was one of the greates Military Leaders and Generals of all time, had he not made some silly mistakes, imagine what an empire he would've forged.