In 1967, the journal Nghiên cứu lịch sử published an article entitled “We Should Study the Issue of the Hồng Bàng Period.”
This article begins by noting that in the study of the history of Vietnam, one issue which must be resolved concerns the question of the Hồng Bàng period, that is, the period when the Hùng Kings supposedly ruled. The authors then go over the traditional story of this period and note that it definitely contains elements which are legendary or mythical in nature. They then discuss the work of scholars who they feel have emphasized the legendary aspects of this period.
They state, for instance, that French scholars considered this a legendary period and that the Hùng Kings were a later creation. They also note that the colonial-era Vietnamese history, Trần Trọng Kim, wrote that it was not certain that the information about the Hồng Bàng period was true. Finally, the authors also state that many historians in the South argue that the Hồng Bàng period and the Hùng Kings never existed.
The authors then note that in contrast to these historians, over the course of the preceding decade, scholars in the DRV had taken the potential reality of the Hồng Bàng period seriously and had conducted research which “proved that the individuals whom we still call the Hùng Kings were not legendary or mythical individuals, but were people made of flesh and bones who had lived and been active around the time of the first millennium B.C.E.” 
This article concludes by saying that if the ancestors of the Vietnamese truly created a “civilized society” (xã hội văn minh) in the first millennium B.C.E., then this shows that the Vietnamese nation(ality) was the earliest to flourish in Southeast Asia and that it created a unique culture of its own in northern Vietnam. This, the authors argue, is something to be proud of, for the Vietnamese are a nationality which has existed for a long time and has its own culture. It has had to fight off invading bandits many times, but has never been assimilated. The authors then state that “now we will definitely defeat the American empire and complete the task establishing the independence and unity of the Fatherland.” 
This article contrasts the work of French, colonial-era, and South Vietnamese scholars with the work of scholars in the DRV. The contrast which is made, however, is both inaccurate and deceiving.
To say that there were no “Hùng Kings” does not mean that there were no people living in the Red River Delta in the first millennium B.C.E., or that there was no political entity there. None of the people whom the authors of this article criticize had ever said that there were no people or polities in the Red River Delta at that time. Nonetheless, that is what this article either implies or states directly.
What these scholars said was that the information which was recorded in the ĐVSKTT about the Hồng Bàng period was not true. They argued that the people who lived in the Red River Delta in the first millennium B.C.E. were not descended from Shen Nong, and that they did not call their leaders “Hùng King.” However, these scholars did not deny that there were people who lived in the Red River Delta in the first millennium B.C.E. and that these people had rulers.
What this means is that these scholars felt that if you could go back in time 2,500 years to the Red River Delta, you would have found people living there in either a polity or polities, and that if you could have asked the ruler of a polity there what he was called and where he came from, he would not have said that he was called the “Hùng King,” and he would not have said that he was descended from Shen Nong, Kinh Dương Vương and Lạc Long Quân.
However, all of the scholars whom are referred to in this article, from Henri Maspero, to Trần Trọng Kim to historians in South Vietnam in the 1960s, acknowledged that there were people living in the Red River Delta in the first millennium B.C.E. and that they created a complex society.
So what this article does is that it conflates the statements which these scholars made about historical texts, with historical reality. These scholars did not make statements about historical reality. They made statements about historical texts which had been written 1,500 years after the period they purported to describe.
This is a very important distinction, and it is one which got lost in the 1960s. In the 1950s and 1960s, scholars in both the North and the South had trouble figuring out how to reconcile the historical information about the past with the archaeological, linguistic and ethnological information which they began to examine.
In the early 20th century, Henri Maspero’s impulse had been to say that the Vietnamese historical record is not helpful in examining the early history of Vietnam. My guess would be that if he could have lived into the 1960s, then he would have been very excited to follow the information which was emerging from other disciplines.
Where everything eventually went wrong, however, was when there was a push to unite the historical information with information from archaeology, linguistics and ethnology. In other words, there was a push to link historical texts with historical reality by relying on evidence from the disciplines of archaeology, linguistics and ethnology. In this article you can see this already happening.
What some of the scholars whom this article criticize had shown is that there are enormous problems with the Vietnamese historical texts. Those problems were never resolved, and then this push to links historical texts with historical reality took place. This then created a mess. What scholars should have done, is to use the information from archaeology, linguistics and ethnology to try to understand the past, and to ignore what is written in the ĐVSKTT about the Hồng Bàng period.