In the year 1258, more than 100,000 soldiers amassed outside the great Islamic city of Baghdad. They were the Mongol Army, led by the grandson of the fearsome Genghis Khan. Within weeks, they'd left the city – which had stood as the center of power and commerce in the Muslim world for nearly 500 years – smoldering in a grotesque heap. And that was just the beginning. The Mongols would continue to push West, conquering Muslim cities until there was just one left in their way: Cairo.In the valley where it is said David once met Goliath, an unlikely group of slave soldiers fought a battle that would decide the fate of the Islamic world. A battle you may never have heard of that's as important to world history as D-Day or Gettysburg. It's a story full of personal and societal rivalries, political scheming, vengeance, and treachery – a real-life Game of Thrones. The Battle of Ayn Jalut.