Vietnamese historical sources record that the earliest kingdom in the area of what is today Vietnam, that of the Hùng kings, had a capital at a place called Phong Châu 峯州. This cannot possibly be true. To understand why, we need to learn about the second half of this name – Châu.
The term châu/zhou appears in many place names. When those place names were established, the term châu/zhou referred to an administrative unit. What is confusing, however, is that this term has not always referred to the same administrative unit over time.
The term châu/zhou was first used to describe the 9 territories which China was divided into in distant antiquity. During the period of the Zhou Dynasty this term was then used to designate an administrative unit of 2,500 families. Charles Hucker, in his A Dictionary of Official Titles in Imperial China, translates this as “township.” From the Han to the Sui, Hucker says that châu/zhou came to designate a “region,” that is, “a jurisdiction of intermediate coordination between the central government and a cluster of neighboring commanderies.” Below commaneries you then had districts.
What then occurred during the period of the Sui Dynasty and into the early Tang was something very confusing. Regions (châu/zhou) were abolished, and then later, commanderies were renamed “châu/zhou,” that is, the exact same term which had previously referred to “regions,” an administrative unit above the level of commandery. Hucker translates “châu/zhou” at this point as “prefecture.”
During the Tang you then have prefectures (châu/zhou) in place of the old commanderies, and districts (縣, huyện/xian).
So the term, châu/zhou, referred to different administrative units at different times. That can create problems in understanding what it refers to at different points in history. For example, the Sui established “Phong Region” while under the Tang there was a “Phong Prefecture,” both of which were “Phong Châu.”
There are, however, other problems with this term. Most Chinese place names consist of two characters. Then when you indicate the administrative unit which a place name refers to, you end up with three characters. So “Giao Chỉ/Jiaozhi Commandery” was 交趾郡 Jiaozhi jun/quận Giao Chỉ.
For some reason, however, the term châu/zhou was used differently. It was always combined with a single character. Therefore, you had names like Phong Châu and Guangzhou. Because these terms only consist of two characters, I think there has been a tendency to not translate châu/zhou, so that such place names will sound like other place names, like Giao Chỉ/Jiaozhi. However, if you do not translate châu/zhou, you lose specificity, and at times it is important to know that châu/zhou is referring to a specific administrative unit.
Yet one more problem is the fact that sometimes a name like “Phong Châu” was used to refer not to the entire region or prefecture, but to the administrative capital of that region or prefecture. And finally, sometimes you find writers in later centuries using these terms anachronistically.
So what should we do? One solution is to not translate châu/zhou. However, again, that creates problems when it is necessary to differentiate between châu/zhou and other administrative units at a given time.
In any case, to get back to the issue of Phong Châu as the supposed capital of the kingdom of the Hùng kings – first, such a capital would not have had such a clearly Chinese name. Second, the term “Phong Châu” does not predate the Sui Dynasty. That is when it was first used to indicate “Phong Prefecture.” So the Hùng kings could not possibly have had a capital called Phong Châu.