There can be few events in history so little known as Chinghiz Khan's wars with Hsi Hsia. Even in works dealing with the conqueror's life, one finds hardly more than a brief sketch of his conquest of this state. Doubtless this is due to the principal records extant on Hsi Hsia being written in Chinese. Many of these must include material originally drawn from Hsi Hsian documents, but to-day the latter are very rare, and until recently there was no one who could read them. Hence most of what has come down to us is from the pens of enemies, and even this is little known to students of Chinese or Mongol history. Yet in its day Hsi Hsia ranked among the great powers of Asia, and next to the empires of Chin and Khwarizm, was the strongest state overthrown by Chinghiz Khan.