Genghis Khan was the greatest conqueror the world has ever known. He and his sons vanquished peoples from the Adriatic to the Pacific. The Mongols eventually reached Austria, Finland, Croatia, Hungary, Poland, Vietnam, Burma, Japan and Indonesia. The Mongol Empire covered 12 million contiguous square miles – an area almost as large as Africa and larger than the continent of North America. By contrast, the Roman Empire was about half the size of the continental USA. By 1240 Mongol conquests covered most of the known world. Genghis and his sons waged major wars on two fronts simultaneously and conquered Russia in winter – both feats that eluded Napoleon and Hitler. How was this possible for a land of 2 million illiterate nomads? The answer was a quantum leap in military technology that brought mounted archery to its acme. The speed and mobility of Mongol archers, the accuracy of their long-range shooting and their uncanny horsemanship, allied to Genghis’s ruthless ‘surrender or die’ policy and his brilliant perception that this gave him the possibility of living off tribute from the rest of the world, combined to make the Mongols unbeatable. As Basil Liddell Hart pointed out, Genghis was a military innovator in two important respects: he realised that cavalry did not need to have infantry backup and he grasped the importance of massed artillery barrages.