Genghis wages his last campaign. The “oceanic ruler” leads his army south for the last time, to quash disobedience in the Chinese kingdom of Xi Xia. Unable to penetrate the walls of Ningxia, the capital, the Mongol soldiers divert water from a nearby canal to create a roaring flood that impels the city to surrender. Genghis, now on his deathbed, orders that Xi Xia be wiped from the face of the earth. Obedient, the Mongols level whole towns, killing or enslaving the inhabitants. To this day, the kingdom remains, as journalist Mike Edwards put it, “a historical blur.”   © 1997 National Geographic Society. All rights reserved.