In 221 BC, Emperor Qin Yingzheng eliminated the last vassal state, unified the Central Plains, and became the first emperor of a feudal dynasty in Chinese history. During his reign, he repeatedly summoned soldiers and horses to search for the legendary "elixir of immortality". For this reason, there has been a craze among the people to find the medicine of "immortality". In his later years, Qin Shihuang ordered to recruit a group of "Qilin Envoys" who were directly under his control and became envoys specializing in searching for the "elder of immortality". As a result, people from all over the country went to Xianyang, Guanzhong, to participate in the selection competition of the 'Qilin Envoy'.