The vassal emperor of Western Xia had refused to take part in the war against the Khwarizm, and Chinggis had vowed punishment. While he was in Iran, Western Xia and Jin had formed an alliance against the Mongols. After rest and a reorganization of his armies, Chinggis prepared for war against his foes.

By this time, advancing years had led Chinggis to prepare for the future and to assure an orderly succession among his descendants. He selected his son Ogedei as his successor and established the method of selection of subsequent khans, specifying that they should come from his direct descendants. Meanwhile, he studied intelligence reports from Western Xia and Jin and readied a force of 180,000 troops for a new campaign.

Late in 1226, when the rivers were frozen, the Mongols struck southward with their customary speed and vigor. The Tangut, well acquainted with Mongol methods, were ready, and the two armies met by the banks of the frozen Huang He. Despite a Western Xia army of more than 300,000 troops, the Mongols virtually annihilated the Tangut host.

Pursuing energetically, the Mongols killed the Western Xia emperor in a mountain fortress. His son took refuge in the great walled city of Ningxia, which the Mongols had failed to conquer in earlier wars. Leaving one-third of his army to take Ningxia, Chinggis sent Ogedei eastward, across the great bend of the Huang He, to drive the Jin forces from their last footholds north of the river. With the remainder of his troops, he marched southeast, evidently to eastern Sichuan Province, where the Western Xia, the Jin, and the Song empires met, to prevent Song reinforcements from reaching Ningxia. Here he accepted the surrender of the new Western Xia emperor but rejected peace overtures from Jin.

A premonition of death caused Chinggis to head back to Mongolia, but he died en route. On his deathbed in 1227, he outlined to his youngest son, Tului, the plans that later would be used by his successors to complete the destruction of the Jin empire.

Data as of June 1989