Once upon a time, in the land called Lac Viet, there was a saint named Lac Long Quan, whose mother was a fairy but the father was a dragon. He was extraordinarily strong and had many miracles. He usually lived under the water and sometimes turned to the land to help people suppressing demons, taught them to grow rice and cut wood for building houses.
He then got married with Au Co - daughter of Agriculture Saint - and the couple lived in harmony in Long Trang Palace on the land. Later Au Co gave birth to a 100-egg bag hatching to 100 sons.
Once day Lac Long Quan felt that it was impossible for him to live permanently like that so he told his wife that:
- I'm a son of dragon and I accustomed to live under the water while you belong to fairy race in the land. We could not share our lives for long so I will take 50 of our sons to settle down into the sea, the remainder will follow you to go up to the mountain. Although we separate, remember to help and protect each other in need. Don't forget my words.
The wife and all the sons obeyed him then they said farewell.
The eldest son, who had followed the mother with 49 brothers, attained the highest honors as King Hung. He set up his capital in Phong Chau and gave country the name Van Lang. There were military and civilian officials in the court. Throne would be ceded to the eldest son called King Hung from generation to generation
For the story Vietnamese are always proud of the noble origin - dragon's children and fairy's grand children.