There are several legends surrounding the origin of the festival. In Vietnam, the best known version tells the story of Qu Yuan, a celebrity in the Chinese history. A statesman and poet, Qu Yuan lived in his state of Chu in southern China in the Warring States period (481-221 BC).
At the time, Qin, a state in the North, proposed a peace treaty and asked the king of Chu to sign it. Knowing that Qin had no intention to honor the agreement, Qu Yuan advised his king to refuse the treaty. Not only did the king sign the treaty but he also sent Qu Yuan into exile.
Later the unprepared Chu was easily defeated by Qin. Learning of the news, on the fifth day of the fifth lunar month of 278 BC, Qu Yuan drowned himself.
In Vietnam, the story is not very popular, but Tet Doan Ngo is a popular event. As a tradition, Vietnamese people consider the festival an occasion to symbolically kill crop-damaging insects.
At dawn of the fifth day of the fifth lunar month, children are treated with a variety of foods, and pink pigment is applied to their heads, chests and navels. It is believed that these practices can help kill insects.
At noon, people go out to pick leaves of the fifth day. That time of the day is believed to be the best throughout the year for leaf picking as leaves in this period have the best effect in disease treatment.
Some people try to find mugwort leaves to weave them into the shape of the animals of the year. These miniature animals are hung in front of the main door as people believe they can chase away bad spirits.
However, Tet Doan Ngo in Vietnam is characterized by a special food - banh u tro, a kind of cake made of glutinous rice soaked in water with wood ash. The way to prepare the water gives the cake its name. To make delicious banh u tro, rain water and ash of mangrove firewood must be used. After a month, water with ash is used to soak glutinous rice. Due to this kind of specially treated water, the outer coat of the cake is translucent.
Two kinds of banh u tro can be distinguished: those with and those without green bean core. Both have a pyramid shape, which makes them different from other cakes.
During the week of the festival, banh u tro is available in the streets of HCMC. With a wire basket full of banh u tro on the back of their bicycles, these vendors stop in front of market gates or ride around town to sell their homemade products.