History and Development of the Mid-Autumn Festival

The term "Mid-Autumn" first appeared in the book Rites of Zhou (周礼), written in the Warring States Period (475–221 BC). But the term only related to the time and season; the festival didn't exist at that point.
In the Tang Dynasty (618–907 AD), it was popular to appreciate the moon. Many poets liked to create poems related to the moon when appreciating it. There is a legend that Emperor Xuanzong of the Tang Dynasty visited the Moon Palace in his dream and heard a wonderful song.
In the Northern Song Dynasty (960–1127 AD), the 15th day of the 8th lunar month was established as the "Mid-Autumn Festival". From then on, sacrificing to the moon was very popular, and has become a custom ever since.
During the Ming Dynasty (1368–1644 AD) and the Qing Dynasty (1644–1912 AD), the Mid-Autumn Festival was as popular as Chinese New Year. People promoted many different activities to celebrate it, such as burning pagodas and performing the fire dragon dance.
Worshiping the moon entailed placing a large table in the middle of the yard under the moon, and putting offerings, such as fruit and snacks, on the table.
Nowadays, many traditional activities are disappearing, but new trends have been generated. Most workers and students regard it as a public holiday to escape work and school. People go out traveling with families or friends, or watch the Mid-Autumn Festival Gala on TV at night.

Stories of 3 Origins — Sacrificing to the Moon, Parties at Night, and Eating Mooncakes

Sacrificing to the Moon — Earliest Origins of Ancient Worship moon worshipMoon worshiping
Ancient Chinese emperors worshiped the harvest moon on the 15th day of the 8th month of the Chinese lunar calendar, as they believed that the practice would bring them a plentiful harvest the following year.
The custom of offering sacrifices to the moon originated from worshiping the moon goddess, and it was recorded that kings offered sacrifices to the moon in fall during the Western Zhou Dynasty (1045–770 BC).
The sacrificial offerings include apples, plums, grapes, and incense, but mooncakes and watermelons (pomelos in the south) are essential. The watermelon's (or pomelo's) skin is sometimes sliced and opened up into a lotus shape when offered as a sacrifice.