Professor Zhang of Northwest University said that Kaiyuan Gate was the starting point of Chang 'an Silk Road in Sui and Tang Dynasties, only two sides away from Chang 'an International Trade Market, and there was a landmark "Li Hou" outside the gate with the title "Xiji Road is 9,900 Li", not to mention Wan Li, indicating that people who travel far away are not traveling in Wan Li. Although Wan Li was not mentioned, according to Zi Tongzhi Jian, "it was a prosperous Qiang in China at that time, and it was 12,000 miles from Anyuanmen to the west of the Tang Dynasty", indicating that there was a direct road to the western regions outside Kaiyuan. At that time, as long as the mileage from Chang 'an to the western regions was mentioned, most of them started from opening the city gate. In the eighth year of Tang Tianbao (749), a "vibration brigade pavilion" was built outside Kaiyuan Gate to show that the soldiers waiting for the Western Expedition were returning to the team.
As an international metropolis at that time, Chang 'an City in Tang Dynasty was particularly convenient for external traffic, and Waiguo City Gate, as the main passage in and out of Beijing, became the joint point of Chang 'an's external traffic. Kaiyuan Gate is the node connecting the Silk Road and the main roads in the city. The Silk Road in Sui and Tang Dynasties started from Chang 'an, started from Kaiyuan Gate to the west, passed through Hexi Corridor, left Dunhuang and then went west, leading to Central Asia, West Asia and Europe. It is through this Silk Road that a large number of porcelain and silk in China were transported by camel teams from Kaiyuan Gate in Chang 'an to countries and regions in the Western Region, and the "Hu merchants" in the Western Region also brought spices, jewels and medicines to Chang 'an through this Silk Road. These goods are mainly sold in western markets not far from home.