It sounds exaggerated. But by most historical estimates, the richest person to have ever lived wasn’t a modern billionaire. It was Mansa Musa, a 14th-century ruler of the Mali Empire. And his wealth ...

Seven centuries ago there was a man, Mansa Musa, who ruled an empire in West Africa and spent money in such a lavish way that his spending is said to have crashed a regional economy for over a decade.