For students of economics and ancient civilizations alike, the strange economy of the Incan Empire is fascinating. Annalee Newitz writes for io9:
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.
Centered in Peru, Inca territory stretched across the Andes’ mountain tops and down to the shoreline, incorporating lands from today’s Colombia, Chile, Bolivia, Ecuador, Argentina and Peru – all connected by a vast highway system whose complexity rivaled any in the Old World. The Inca Empire may be the only advanced civilization in history to have no class of traders, and no commerce of any kind within its boundaries. How did they do it?
Many aspects of Incan life remain mysterious, in part because our accounts of Incan life come from the Spanish invaders who effectively wiped them out.
For the Incas, coca and alcohol served simultaneously as keys to the sacred and tools of coercion and control, 
