Legend of Lac Long Quan - Au Co has been passed by tradition in Vietnam for thousands of years now.

   According to the legend, Lac Long Quan's father was Kinh Duong Vuong Loc Tuc, belonging to Emperor Shen Nong descent, and his mother was Female Dragon who was Dong Dinh Lake Deity's daughter. Lac Long Quan brought his mother attribute (Dragon), so he had her hereditary characteristics, prefering water to land. When being grown-up, Lac Long Quan was in throne named Hung King and ruled Lac Viet country with temperate climate, seas nearby, beautiful landscapes, and green trees.

   After killing monsters from coastal to mountainous areas by wonder-working power, Lac Long Quan built palace both on the land and under the water, and introduced people about farm-work, living style. Lac Long Quan married Au Co, De Lai King's Daughter in the North (also belonging to Emperor Shen Nong descent).

   Au Co gave birth to 100 sons from a womb after 3 years' & 10 days' pregnancy. When their children grew up, Lac Long Quan told Au Co that he & his wife belonged to Dragon' & Fairy descents, respectively; so, water & fire were incompatible, one was accustomed to water and the other to land. Then, each 50 sons followed their father to the sea, and their mother to the mountain. They had to communicate to each other promtly in case of necessity.

   Then, they took their children down to sea and up to mountain to make their living. Although this tale is a legend, it has long been deeply engraved not only in Vietnamese people's memory but also in the vestige, practices, customs of several localities in Vietnam.

   For example, in Binh Da village, Binh Minh commune, Thanh Oai district, Ha Tay province where Lac Long Quan started to take his children to the sea, now, there is Noi Communal House to worship Lac Long Quan, a national ancestor of Vietnam. The house was built in 1918 (Year of the Horse - Khai Dinh) with the large, spacious scale on the high land with secular trees.

   The Communal House retains valued material, on the gate of main room is a big horizontal lacquered board engraved with Chinese characters "Vi Bach - Viet To" (an old ancestor of 100 sons) and typically, a board painted with brilliant vermilion & gilded showing Lac Long Quan together with all officials of the court watching boat-racing, a popular festival of ancient Vietnamese people. The Noi Communal House was ranked among Cultural & Historical relics in 1985.

   In Hien Luong village, Thao River district, Phu Tho province, where Au Co started to take her children to mountain, to introduce people about cultivation of paddy & mulberry, raising of silk-worm, now, there is Au Co Mother Saint Temple.

   The Temple was built on Hien Luong green paddy-field under Late Le dynasty (1465). In the temple, there is fine Au Co statue, being engraved with realistic style, expressing Au Co as a Fairy both pretty & kind-hearted and good at external relation, and her elder son's statue who was a talented general, faithful to his mother, & raised to the position of Super Deity".

   The Temple was ranked among Cultural & Historical relics in August, 1991. Lac Long Quan & Au Co's memory will live forever in Vietnam's national pride. Therefore, on the 2nd of the 6th lunar month yearly, Binh Da commune is busy with festival joy:

   Hien Luong commune (Phu Tho), on the 7th of the 1st lunar month celebrates Au Co Mother Temple festival to welcome the stream of visitors with sincere veneration & pride.

   On 04.4.2000, Department General of Posts & Telecommunications (DGPT) issues the stampset "Vietnamese Legend of Lac Long Quan and Au Co" consisting of 6 values showing the core of the legend: Vietnamese nation stems from Dragon & Fairy descent. Founding state & building border started since Lac Long Quan & Au Co's initial stage. Vietnamese ethnic group community is brotherly in the same house (was born from a womb) that made more clarification for familiar, scared Vietnamese word "Dong bao" (i.e.: in the same womb).