According to the legend, Lac Long Quan (real name Sung Lam, the son of Kinh Duong Vuong and Than Long Nu) married Au Co (the fairy daughter of De Lai). Au Co then went on to give birth to a pouch filled with one hundred eggs, which hatched into a hundred sons. However, soon thereafter, Lac Long Quan and Au Co separated. 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 reigns 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 bumper 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.

The worship of the Hung Kings, closely related to the ancestral worship traditions of most Vietnamese families, was recognised as part of the Intangible Cultural Heritage of Humanity by UNESCO in 2012.

This year, the Hung Kings Temple Festival is being held in the northern midland province from April 9 to 18 (or the 1st to the 10th day of the third lunar month), along with the Culture and Tourism Week of the Ancestral Land.