Ya-lung River - China : Wade–Giles romanization Ya-lung Chiang , Pinyin Yalong Jiang long secondary tributary of the Yangtze River in central and southern China. The Ya-lung rises in the Pa-yen-k'a-la Mountains in Tsinghai Province at an elevation of nearly 16,500 feet (5,000 m). The upper stream flows southeastward to the south of the Pa-yen-k'a-la Mountains into northwestern Szechwan Province. Below Kan-tzu it swings southward to flow along the western side of the Ta-hsüeh Mountains. After making some wide loops in its course at the southern end of this range, the river flows into the Chin-sha River near Tu-k'ou on the border of Yunnan Province. The Ya-lung is torrential for most of its course and carries a very large volume of water, but it is useless for navigation. Until comparatively recently, its lower course, south of the Ta-hsüeh Mountains, was the limit of effective Chinese penetration to the West; its valley provided the major trade route from Ch'eng-tu in Szechwan to Ta-li in Yunnan and to Southwest China and northern Myanmar (Burma).