What is the origin of Mid-Autumn Festival? Detailed answer

The fifteenth day of the seventh lunar month is the Mid-Autumn Festival. It is said that Taoism regards this day as the birthday of local officials, and people in the southern region will sacrifice their dead families during this time. There is a legend that "July 15 is the Central Plains, and the death of Yan opens the door of hell", so the Mid-Autumn Festival is also a ghost festival, named after the Central Plains in the middle of the 24 solar terms.