Moon cakes, or Mid-Autumn cakes, are Mid-Autumn Festival foods in all parts of East Asia, and they are called Bánh trung thu in Vietnam. The custom of eating moon cakes in the Mid-Autumn Festival began in the Tang Dynasty. In the Northern Song Dynasty, moon cakes were called "palace cakes", which were popular in the court and also spread to the people, commonly known as "small cakes" and "moon groups". Later, it evolved into a circle, meaning reunion and beauty. Moon cakes were originally cakes shaped like a full moon, with a round appearance, indicating reunion, and later they also had square or other shapes. Eating moon cakes in the Mid-Autumn Festival, like eating zongzi in the Dragon Boat Festival and glutinous rice balls in the Lantern Festival, is a traditional folk custom in China.