Helan Mountains
In August 1226, Mongol troops approached Liangzhou, the second-largest city in Western Xia, which surrendered without resistance. In Autumn 1226, Genghis crossed the Helan Mountains, and in November laid siege to Lingwu, a mere 30 kilometers from the capital. At this point, Xianzong died, leaving his relative, Xian, posthumously Emperor Mozhu of Western Xia, to deal with the Mongol invasion.