How did the Inca Empire use relay runners and posthouses?

The Inca Empire utilized a highly efficient relay system to facilitate communication and transportation across its vast territory, which spanned the Andean highlands and the Pacific coast. Because the Inca did not have a system of writing, they relied on this organized network to transmit information for government and military purposes.12

Key components of this system included:

• Relay Runners: Messages were carried by foot messengers who operated a relay service. These runners could transport information at a rate of approximately 150 miles (241 km) per day.13
• Quipu: Instead of written text, these messengers carried quipu—knotted cords used for bookkeeping and historical recording—to convey data across the empire.21
• Road Network and Posthouses: The Inca maintained a vast road system, including two major north-south routes. Along these roads, the Inca established way stations known as tambos (posthouses) at frequent intervals. These stations provided essential support, including barracks and warehouses, to facilitate the movement of messengers and caravans.24

This infrastructure was strictly reserved for government and military business, ensuring the central administration could maintain control over its expansive domain.1