In 742 AD, Tang Xuanzong Li Longji was complacent, indulged in pleasure and did not care about state affairs, and changed the Yuan Tianbao. After Nayang Yuhuan became a concubine, she became even more addicted to wine. In 755 A.D., both Pinglu, Fanyang, and Hedong three towns made An Lushan take advantage of the emptiness and corruption within the Tang Dynasty to kill Yang Guozhong in the name of rebellion in Fanyang (now Beijing), which lasted for a total of 8 years, and was known as the Anshi Rebellion. Although the war was peaceful, the economy of the war-torn areas in the Central Plains was seriously damaged, and the invasion of Tibet into the Tang Dynasty was becoming more and more frequent, and the national strength of the Tang Dynasty was greatly weakened and the Tang Dynasty went down the road of decline.

In 806 AD, Tang Xianzong Li Chun ascended the throne with the year name Yuanhe. He often reads the lists of previous dynasties, and every time he reads the story of Zhenguan and Kaiyuan, he admires it. Taking this as an example, Xianzong conscientiously summed up historical experience, paid more attention to giving play to the role of ministers, and dared to use capable ministers as prime ministers. Great results were achieved in the reduction of the Yuan and feudal domains.

After the Anshi Rebellion, Zheng Xunyu, the prime minister of Daizong, and Zheng Qin and Zheng Lang, who were also prime ministers with his two sons, saw and experienced the blossoming and falling of flowers from Tianbao to the end of the Tang Dynasty. In the 10th year of Dazhong, in 856 AD, Zheng Lang died, leaving a son, surnamed Zheng Mingyu Zhongjue.

After Zheng Lang's death, Tang Xuanzong Li Chen was instructed by the eunuchs to raze Zheng Lang's mansion to the ground and behead the Zheng family, probably because Zheng Lang fought against them everywhere during his lifetime.

Zheng Yu was 20 years old, and one night, under the cover of the housekeeper, escaped.

This is where the story begins.