The city they approached was the capital of Shah Muhammad of the Khwarezm, the center of an empire that included parts of modern-day Afghanistan and Iran. Earlier, the Shah had executed the Mongol Ambassador and had sent back the man's head to Genghis Khan, infuriating the Mongol leader. Shah Muhammad had 110,000 troops in the city, but most were poorly disciplined and fled even before the Mongol army arrived. After just a day's fighting, the city gates were opened, and the shah's people were forced to beg the Mongols for mercy, which they did not receive.