The Lantern Festival (Upper Yuan Festival) is the 15th day of the Lunar New Year, usually in February or March of the Gregorian calendar. As early as the Western Han Dynasty (206 BC - 25 AD), it became a festival of great significance.
The predominat activity of the day is to enjoy the lights. Throughout the Han Dynasty (206 BC - 220 AD), Buddhism flourished in China. An emperor heard that Buddhist monks would check the relics on the fifteenth day of the lunar month, recall the cremation of the Buddha's body, and use lanterns to worship the Buddha, so he ordered the day to light the lanterns in the palace and temple to show respect of the Buddha. Later, Buddhist ceremonies developed into a grand festival for ordinary people, and their influence expanded from the Central Plains to the whole of China.