The first month is the first month of the lunar calendar, and the ancients called "night" "night". The fifteenth day of the first month is the first full moon night in a year, so it is called "Lantern Festival". According to the Taoist saying of "Sanyuan", the 15th day of the first month is also called "Shangyuan Festival". Since ancient times, the Lantern Festival custom has been dominated by the warm and festive custom of watching lanterns.
The gods worshipped by Wudou Midao, an important faction of Taoism at the end of Han Dynasty, were Tianguan, Diguan and Shuiguan. They said that heavenly god blesses the people, the Diguan pardoned sins and Shuiguan relieved Eritrea, and they matched three officials with three yuan, saying that Shangyuan Tianguan was born on the 15th of the first month, Zhongyuan Diguan was born on the 15th of July and Xiayuan Shuiguan was born on the 15th of October. Taoism in Wei and Jin Dynasties matched season and climate with three officials, and designated the 15th day of the first month as Shang Yuan, the 15th day of July as Zhong Yuan and the 15th day of October as Xia Yuan, which were collectively called "Sanyuan".