Temüjin grew up in poverty on the steppe. As an adult he combined inter-tribal alliances, military innovation, and harsh discipline to bring the Mongol steppe under his control step by step. At a kurultai on the banks of the Onon in 1206 he was proclaimed Genghis Khan, 'universal ruler'. By his death in 1227 the empire already stretched from Central Asia through northern China to Iran.

His successors extended it further: in 1241 a Mongol army defeated the combined European forces in Hungary, in 1258 Baghdad fell and the Abbasid Caliphate ended, in 1279 southern China (the Song dynasty) was absorbed. At its peak the empire ran from the Pacific to Hungary, from Siberia to the Persian Gulf — some 24 million square kilometres. It then split into four great khanates that became progressively independent.

The invasions exacted a heavy toll: many cities were destroyed, vast regions saw sharp population declines. Yet the empire also created a long peace known as the Pax Mongolica: the Silk Road reopened, merchants, envoys, and travellers (Marco Polo, Ibn Battuta, the multinational court of Rashid al-Din) carried knowledge across continents. Chinese gunpowder, paper, and printing technology flowed west; Islamic astronomy and medicine flowed east. Much of modern Eurasia's cultural geography was shaped, in a sense, in the wake of this 13th-century Mongol corridor.