Zhang Qian went to western immortals for help several times.

Zhang Qian went to the western regions twice from the second year of Jianyuan (before 139) to the third year of Yuanshuo (before 126), Zhang Qian went to the western regions twice in the first year of Yuanshou (before 1 19), and Zhang Qian went to the western regions twice in the second year of Jianyuan (before19) After Dawan (now Fergana) and Kangju (now Samarkand) to the upper reaches of the Amu Darya River, Da Yue was finally found. But at this time, the big moon family had already surrendered to Daxia through war, lived and worked in peace and contentment in this area, and never wanted to take revenge on the Xiongnu again. Zhang Qian was caught by Huns on his way home. Fortunately, he escaped again and returned to Chang 'an. In the fourth year of Yuanshou (before 1 19), Zhang Qian made his second mission to the western regions. This time, his task was to form an alliance with the Wusun people in the Ili Valley, "be kind to Wusun, make him live in his hometown" and "break the Huns' right arm". This time, it successfully reached Chicheng Valley in Wusun, but civil strife occurred in Wusun, which failed to achieve the goal of alliance. However, he took advantage of this opportunity to establish official diplomatic relations with the western regions and Central Asian countries. Although Zhang Qian's two missions failed to achieve the goal of alliance, they broadened people's horizons, established extensive economic and cultural ties between the Han Dynasty and the western countries, developed exchanges between China and the West, and obtained a lot of information on social, economic and geographical exchanges between the western regions and Central Asia, which also played an important role in the development of the northwest by Emperor Wu of the Han Dynasty. This historical event is called "Zhang Qian hollowing out". Although the Silk Road had a history of hundreds of years before the Han Dynasty, Zhang Qian, as a great pioneer, played a very important role in opening up the Silk Road and developing exchanges between China and the West. Then, the advanced Western Han Dynasty finally defeated the Xiongnu. In order to better control Hexi, ensure the smooth flow of the Silk Road and resist the Huns, the Western Han Dynasty successively set up four counties of Wuwei, Zhangye, Jiuquan and Dunhuang. At the same time, in the west of Lop Nur, it passed through Korla and Luntai to the northwest of Kuqa, and built defense systems such as frontier fortress, pavilion and Great Wall. And organized several large-scale immigrants, making the population of Hexi reach about 400 thousand. Secondly, in today's Luntai, the Western Regions Protector was formally established to command the countries in the Western Regions to ensure the smooth flow of the Silk Road. The establishment of the western regions' capital government forced the Huns to give up their ambition to dominate the western regions, marking the beginning of the effective rule of the western Han government. In order to avoid the Taklimakan desert due west, the road leading to the western regions in Han Dynasty was divided into two roads along the edge of the desert. Both roads start from Dunhuang. At that time, Dunhuang set up Yangguan in the southwest and Yumenguan in the northwest to control the two-way access. Dunhuang is in the position of such a transportation hub. With the smooth Silk Road, it became the most dazzling "international city" in the Middle Ages. Silk, iron, jade and lacquerware are shipped out from here, and spices, fabrics, precious stones, pigments and glass from Central Asia, West Asia and Europe enter China. Dunhuang entered its first prosperous period.