The Inca Empire lasted a couple of a hundred years and according to Terence D’Altroy of Columbia University, in a 2007 PBS interview, ‘In terms of square miles, we’re probably talking something like 300,000 square miles’ with a population as high as 12 million. They built elaborate cities and created terraced farms on the mountainsides, all connected by a road network equivalent to about three times the diameter of the Earth and far superior to what the Conquistadors were accustomed to back in Europe.  And all this was achieved without money or internal markets.

In ‘The Incas: New Perspectives’, Gordon Francis McEwan writes: ‘Each citizen of the empire was issued the necessities of life out of the state storehouses, including food, tools, raw materials, and clothing, and needed to purchase nothing. With no shops or markets, there was no need for a standard currency or money, and there was nowhere to spend money or purchase or trade for necessities.’