The Incas and Money
The Incas did not use money. They had gold, silver and precious jewels, but those were used for ornamentation, not for exchanging for food or services. So how did they manage to run such a large government and pay for everything?
Every adult male (who was not royalty or a priest) was required to do free work for the government for a certain number of days each year. People would be assigned duties depending on their skills. The temples, the roads, the palaces, everything was built this way.
Also the Inca Emperor owned all of the land. In each town agricultural land was set aside for the farmers with each plot being divided into three sections. The farmers were allowed to keep anything they grew in one section, but had to give to the government everything they grew in the other two sections. The government would then occasionally distribute this food to the people who performed mita work.