Why did Genghis Khan attack the Tangut state of Xi Xia?

Genghis Khan’s military actions against the Xi Xia state occurred in two distinct phases, each driven by different strategic motivations:

• Initial Conquest (1205–1209): Genghis Khan targeted the Tangut kingdom early in his rise to power to neutralize a potential enemy on his flank. By securing the allegiance of the Xi Xia state, he effectively cleared the path to launch a major campaign against the Jin dynasty in northern China without leaving a hostile power behind him.12

• Subsequent Campaign (1226–1227): The later, more destructive invasion was a punitive response to the Xi Xia king’s refusal to provide military assistance to the Mongols during their expedition against Khwārezm. This campaign, which resulted in the near-annihilation of the state, was also the final military effort of Genghis Khan’s life; he died in 1227 while the conflict was still underway.31