The Inca trail system was an essential part of the success of the Inca Empire. Including an estimated 40,000 kilometers, the road was built for use in all kinds of climate, moving people and goods--and armies when needed--across the length and breadth of the empire.
Two main roads made up the Inca Trail system, one along the coastline of South America between Tumbes (Peru) and Talca (Chile), and one through the Andes highlands between Quito (Ecuador) and Mendoza (Argentina). Many other short routes led to different Inca provincial centers.
McEwan, Gordon F. 2006 The Incas: New Perspectives. Santa Barbara: ABC-CLIO.
Hyslop, John. 1984. The Inka Road System. Academic Press: New York.