Now, however, imagine a world with no money 500 years ago, the most powerful society in South America, the Inca Empire, had no real concept of money The Incas appreciated the aesthetic qualities of rare metals. Gold was the sweat of the sun, silver the tears of the moon labour was the unit of value in the Inca Empire, just as it was later supposed to be in a communist society. But in 1532, the Incas ran into a man whose hunger for money had led him across an ocean. (Francisco Pizarro and his fellow Conquistadores had come from Spain to what they called Upper Peru)