Leaders of Phu Tho province offer incense to Father Lac Long Quan.

The rituals were to express gratitude to Lac Long Quan and Au Co who laid the foundation of the country, and to pray for the nation's prosperity, people’s peacefulness, happiness, and good weather. They demonstrated the Vietnamese time-honored tradition of "When you drink water, remember the source" and the gratitude to predecessors.

Every year, activities worshipping Lac Long Quan and Au Co take place ahead of the death anniversary of the Hung Kings, believed to be the very first founders of Vietnam, on the 10th day of the third lunar month, which falls on April 18 this year.

This year's Hung Kings Anniversary and the Phu Tho Culture and Tourism Week will last 10 days until April 18 at the Hung Kings Temple National Historic Site in Viet Tri City and other localities in Phu Tho province.

According to legend, Lac Long Quan married Au Co, who then went on to give birth to a pouch filled with one hundred eggs, which soon hatched into a hundred sons. Lac Long Quan went to the coast with 50 of the children, while Au Co went to the highlands with the rest.

Their eldest son was made king, who named the country Van Lang and set up the capital in Phong Chau (modern-day Viet Tri city in Phu Tho province), beginning the 18 generations of the Hung Kings. The kings chose Nghia Linh Mountain, the highest in the region, to perform rituals devoted to rice and sun deities to pray for healthy crops.

To honour their great contributions, a complex of temples dedicated to them was built on Nghia Linh Mountain, and the 10th day of the third lunar month serves as the national commemorative anniversary for the Hung Kings.