The Silk Road
The Silk Road was not one road. It was a network of land and sea routes linking China with Central Asia, India, Persia, Arabia and the Mediterranean world. It grew busy after China's Han dynasty sent envoys west in the 100s BCE.
Few merchants travelled the whole way. Instead, goods passed from trader to trader and city to city, and each trader added to the price. Camel caravans crossed deserts and stopped to rest and get water at oasis towns such as Samarkand and Dunhuang.
The routes carried more than silk, spices and horses. Ideas travelled too: Buddhism spread from India into China, and art styles and inventions moved in both directions. Unfortunately, diseases also spread along the same routes.