ECONOMICS - The greatest mystery of the Inca Empire was its strange economy

In the fifteenth and sixteenth centuries, the Inca Empire was the largest South America had ever known. Rich in foodstuffs, textiles, gold, and coca, the Inca were masters of city building but nevertheless had no money. In fact, they had no marketplaces at all. ...

http://io9.com/the-greatest-mystery-of-the-inca-empire-was-its-strange