A 14th-century portrait of Genghis Khan. At the height of his power the Mongol leader ruled about 17% of the world’s landmass from East Asia to the eastern fringes of Europe.

A 14th-century portrait of Genghis Khan. At the height of his power the Mongol leader ruled about 17% of the world's landmass from East Asia to the eastern fringes of Europe.

A 14th-century portrait of Genghis Khan. At the height of his power the Mongol leader ruled about 17% of the world’s landmass from East Asia to the eastern fringes of Europe.