In due order of succession the chief ship passed to Kabul Khan, who in the year 1135 began to encroach on the dominion of Hola, the Kin emperor. He seems to have been induced to commit this act of hostility by a prophecy, to the effect that his children should be emperors, and also by discourteous treatment received on the occasion of his visit to the court of Oukimai. Whatever the cause of umbrage, Kabul Khan made the Kins pay dearly for their arrogance or short-sighted policy. Hola sent an army under one of his best generals, Hushahu, to bring the Mongol chief to reason, but the inaccessibility of his home stood him in good stead. The Kin army suffered greatly in its futile attempt to cross the desert, and during its retreat it was harassed by the pursuing Mongols. When the Kin army endeavored to make a stand against its pursuers, it suffered a crushing overthrow in a battle at Hailing, and on the Kins sending a larger force against the Mongols in 1139, it had no better fortune. Kabul Khan, after this second success, caused himself to be proclaimed Great Emperor of the Mongols. His success in war, and his ambition, which rested satisfied with no secondary position, indicated the path on which the Mongols proceeded to the acquisition of supreme power and a paramount military influence whithersoever they carried their name and standards. The work begun by Kabul was well continued by his son Kutula, or Kublai. He, too, was a great warrior, whose deeds of prowess aroused as much enthusiasm among the Mongols as those of Coeur de Lion evoked in the days of the Plantagenets. The struggle with the Kins was rendered more bitter by the execution of several Mongols of importance, who happened to fall into the hands of the Kins. When Kutula died the chiefship passed to his nephew, Yissugei, who greatly extended the influence and power of his family among the tribes neighboring to the Mongol home. Many of these, and even some Chinese, joined the military organization of the dominant tribe, so that what was originally a small force of strictly limited numbers became a vast and ever-increasing confederacy of the most warlike and aggressive races of the Chinese northern frontier. Important as Yissugei's work in the development of Mongol power undoubtedly was, his chief historical interest is derived from the fact that he was the father of Genghis Khan.