Vietnam, since its founding as in independent state in the tenth century, has developed through a long period of national consciousness building. Over the course of more than a thousand years, there have been remarkable displays in a variety of aspects, such as culture, literature, thought, history and beliefs, but especially in the formation of the mythology centered on the Hung Kings, founding ancestors of Vietnam, a mythological system which has been sustained far long longer than even Japan and Korea's national myths. In the fourteenth century, Vietnamese constructed legend of their ethnic ancestors, which formally became history in the fifteenth century, inscribed in the The Complete Annals of Đại Việt, a work that established a Vietnamese system of historiography. From this time, when myth, history, and religion came to mutually influence one another, until the 20th century, a whole system of beliefs about the Hung Kings was formed, something that was even inherited and carried forward by the atheist Community Party of the Vietnamese government. This paper discusses beliefs of the Hung Kings from the perspective of a Vietnamese nationalistic religion, pointing out how the Hung Kings have moved from a figure of mythology to one of history, thereby constituting a constructive process of a religion that now penetrates Vietnam's national consciousness.