These expeditions were followed by an invasion of the Heung-nou country by a large army, commanded by the two successful generals Wei Tsing and Hokiuping. This movement was attended with signal success, and the Tartars for the time were thoroughly cowed, while the Chinese lost much of their old dread of their desert foe. Years afterwards (110 B.C.) a new Tartar war began, Vouti himself taking command of an army of two hundred thousand men, and sending an envoy to the Tartar king, commanding him to surrender all prisoners and plunder and to acknowledge China as sovereign lord of himself and his people. All that the proud chief surrendered was the head of the ambassador, which he sent back with a bold defiance. For some reason, which history does not give, Vouti failed to lead his all-conquering army against the desert foe, and when, in a later year, the steppes were invaded, the imperial army found the warlike tribes ready for the onset. The war continued for twenty years more, with varied fortune, and when, after fifty years of almost incessant warfare with the nomad warriors, Vouti laid down his sword with his life, the Tartars were still free and defiant. Yet China had learned a new way of dealing with the warlike tribes, and won a wide reputation in Asia, while her frontiers were much more firmly held. The long reign of the great emperor had not been confined to wars with the Tartars. In his hands the empire of China was greatly widened by extensions in the west. The large provinces of Yunnan, Szchuen, and Fuhkien were conquered and added to the Chinese state, while other independent kingdoms were made vassal states. And "thereby hangs a tale" which we have next to tell. Far west in Northern China dwelt a barbarian people named the Yuchi, numerous and prosperous, yet no match in war for their persistent enemies the Tartars of the steppes. In the year 165 B.C. they were so utterly beaten in an invasion of the Heung-nou that they were forced to quit their homes and seek safety and freedom at a distance. Far to the west they went, where they coalesced with those warlike tribes of Central Asia who afterwards became the bane of the empire of Rome. The fate of this people seemed a bitter one to Vouti, when it was told to his sympathetic ear, and, in the spirit in which King Arthur sent out his Round Table Knights on romantic quests, he turned to his council and asked if any among them was daring enough to follow the track of these wanderers and bring them back to the land they had lost. One of them, Chang Keen, volunteered to take up the difficult quest and to traverse Asia from end to end in search of the fugitive tribes.