Dating back to the Hong Bang Dynasty (pre-feudalism period of Vietnam, according to the legend), the story began when the sixth Hung King wanted to find an heir to the throne. He organized a competition for his twenty-one sons, stating that whoever can create the best dishes under the King’s eyes would be chosen as the heir. While other princes searched for the most expensive and the most exceptional dishes, the eighteenth son, Lang Lieu, could not afford to find any such dishes.
One night, he dreamt of a deity who told him: “There is nothing bigger than the sky or the earth, and the rice is the most precious of all. Now use glutinous rice to make Banh Chung, a green thing in the shape of a square, to represent the earth (in ancient times, people thought that the earth was square). It will have a filling made of mung beans and meat symbolizing plants and animals living on earth. You will use green leaves to cover it, representing the care of parents for their children. Then use ground glutinous rice to make Banh Day, a white, dome-shaped thing representing the sky”.
When he awoke, Lang Lieu was very happy and start preparing the two things described by the deity. When Lang Lieu presented his father Banh Chung and Banh Day, the King was very impressed by the taste and the meaning of these two cakes represented. He then declared that Lang Lieu would be the new King, and Banh Chung (the square thing made out of rice) would ever since become the traditional and indispensable dish of the Vietnamese Lunar New Year.