For a brief moment, towards the end of the 12th century, the Muslim world was politically united under one caliph ruling from Baghdad. This political unity, rare in Islamic history, projected itself on the military plane. In West Asia, the Crusaders were ejected from Palestine, Lebanon and Syria. Salahuddin recaptured Jerusalem in 1187. Four years later, in 1191, Muhammed Ghori of Ghazna...

It was the century when three powerful traditions-Islamic, Medieval Christian and Mongol-collided. The aftermath of this collision transformed all three traditions in ways that were profound and basic. The cataclysm of the Mongols was a global event, which left its indelible mark upon human history. It destroyed ancient dynasties, remade human races and fundamentally changed the way people...