How did the Inca run an empire across the Andes without horses or wheels?

The Inca ran their empire along a giant network of roads and a relay of runners. The road system, called the Qhapaq Ñan, or royal road, was the most extensive and advanced transportation system in pre-Columbian South America, about 40,000 kilometres long in total. It carried information, goods, soldiers and people, without the use of wheels, across a territory of almost 2,000,000 square kilometres and about 12 million people.

The roads were real engineering: planned, built and maintained, paved where needed, with stairways to climb steep slopes, bridges, retaining walls and drainage. The network was based on two north-south roads, one along the coast and a more important one inland through the mountains, with many branches. At one-day walking intervals, rest houses called tambos supported travellers and llama herds.

Messages moved fastest, carried by chasquis, the running messengers. Agile, highly trained and fit, a chasqui carried messages as knotted-string records called quipus, spoken information or small packets. Relay stations about 2.5 kilometres apart held fresh runners: the arriving chasqui handed over the message and the next one ran on. Together the relay could deliver a message or a gift up to 300 kilometres in a day.

There was no wheel, and no horses in Peru: everything moved on foot, with llama caravans for heavy goods. The road was so useful that its effects lasted long after the empire. A 2021 study found wages, nutrition and school levels higher within 20 kilometres of the old road, more than 500 years later.