The Mongol Exchange

In the 13th century the Mongols built the largest contiguous land empire in history, stretching from Korea to Eastern Europe. Their conquests were extremely destructive, yet once established, Mongol rule created a period sometimes called the Pax Mongolica, when travel across Eurasia became safer and faster. A relay system of post stations, the yam, and metal passes called paiza let officials and favoured merchants move long distances.

The Mongols deliberately moved skilled people, such as Persian astronomers to China and Chinese doctors to Persia, so technologies, recipes, maps and medical ideas crossed cultures. Travellers like Marco Polo and Ibn Battuta wrote famous accounts, and in Persia Rashid al-Din compiled one of the first attempts at a world history. Historians weigh this exchange against the violence that made it possible, and some argue the same connections later helped spread the Black Death.