Answer: Inca society developed on the slopes of the Andes.
Today, these lands include Peru, Colombia, Ecuador, western Bolivia, northern Chile, and northwest Argentina.
The Inca economy was based on collective work and adapted to one's age. The foundation of the economy was agriculture, developed especially in the mountainous Andes.
Crops stretched down steep slopes, with the terraced system - a sort of stone-walled steps. State lands were cultivated by all fields and production was stored to support the nobility, the priests, and the military. The surpluses were stocked in warehouses installed throughout the empire and distributed in times of grace or times of calamity. To improve land productivity, two resources were used: manure made from llama and bird manure; and irrigation, with tanks and canals.
In order to account for the taxes collected and to control production, the <em>Quipu</em>, meaning knot, was used in Quechua. The <em>quipu</em> consisted of a cord, which was attached to a series of small colored strings, hanging in the form of bangs and with several knots.
