Genghis Khan to Kublai Khan

The steppe runs for five thousand kilometers, from Hungary to Manchuria, a flat sea of grass that most settled people of the medieval world found unremarkable, inhospitable, and easy to ignore. The nomads who lived on it were, in the view of Chinese court officials and Persian administrators, raiders at best and nuisances at worst — a problem to be managed with walls and tribute payments, not a threat to civilization itself.

They were wrong about this.

In the late twelfth century, a boy named Temüjin was born into the Borjigin clan of the eastern Mongolian steppe. His father, a minor chieftain, was poisoned by a rival Tatar clan when Temüjin was around nine years old. The clan abandoned his family immediately afterward, unwilling to follow a widow and her children. Temüjin spent his adolescence surviving, sometimes barely, through a combination of cunning, ferocity, and an unusual ability to attract and retain loyal followers.