This country had admitted the supremacy of the emperor, but not until now did it become part of the empire, which it has since remained. The last warlike act of Taitsong's life was the invasion of Corea.
Wou Sankwei, having rid himself of his great enemy, now became anxious for the departure of his allies. But he soon found that they had no intention of leaving Peking, of which they were then in full control. At their head was Taitsong's young son, still a child, yet already giving evidence of much sagacity.
The Sanpou also agreed to accept Chinese education, and as his reward Taitsong gave him one of his daughters as a wife. It is stated that one of his first reforms was to abolish the national practice of painting the face, and he also built a walled city to proclaim his glory as the son-in-law of the Emperor of China. During Taitsong's life there was no further trouble on the side of Tibet.
Taitsong's new army was soon put to the proof. The Tartars were in arms again, a powerful confederacy had been formed, and China was in danger. Marching into the desert with his disciplined forces, he soon had his enemies in flight, forced several of the leading khans to submit, and spread the dread of his arms widely among the tribes.
Taitsong's reign closed under the cloud of these reverses; but, on the whole, it was successful and creditable, marking an improvement in the condition of the country and the people, and the triumph of the Sungs over at least one of their natural enemies. His son and successor, Chintsong, must be pronounced fortunate in that the first year of his reign witnessed the death of Yeliu Hiuco.
Taitsong's premature death, due, in all probability, to the incompetence of his physicians, cut short a career that had not reached its prime, and retarded the conquest of China, for the supreme authority among the Manchus then passed from a skillful and experienced ruler into the hands of a child.
Kashgaria was then, for the first time, formed into a province under the name of Lonugsi, and Lichitsi, one of the emperor's best generals, was appointed Warden of the Western Marches. Some of the most influential of Taitsong's advisers disapproved of this advanced policy, and attempted to thwart it, but in vain.
The Manchus seem to have been a little alarmed by the boldness of Taitsong's scheme, and they might have hesitated to follow him if he had given them any time for reflection, but his plans were not fully known until his forces were through the Dangan Pass on the march to the capital.
The last years of Taitsong's life were spent in conducting repeated expeditions into the provinces of Shansi and Pechihli, but the strength of the fortresses of Ningyuen and Shanhaikwan on the Great Wall effectually prevented his renewing his attempt on Pekin.
The Chinese chroniclers declare that the Tartars were so impressed by Taitsong's majestic air and remonstrances that they agreed to retire, and fresh vows of friendship and peace were sworn over the body of a white horse at a convention concluded on the Pienkiao bridge across the Weichoui River.