Huazhong, Jinguancheng

During the Changqing period, there were many vassal towns in the Tang Dynasty. Among them, Jiannan Road is an important border town with a high degree of freedom in military and political power. Xichuan Jiedushi Du Yuanying secretly communicated with Tibet, which led to the attack on Chengdu. The central government appointed Duan Wenchang, the "cold-faced judge", as the new military governor. After Duan Wenchang took office, he uncovered problems such as corruption among officials and businessmen and depletion of salt sources. He organized people and horses to develop salt wells, and at the same time searched for the legendary underground treasure in Jiannan Road. His son Duan Chengshi, elite soldier Wu Qing, and Taoist Xuanyi were ordered to start the expedition.