Abstract
The purpose of this article is to criticize the view of ancient Vietnamese agriculture held by some Japanese historians of Vietnam that 'Lạc Điẽn, ' or ricefields of Lạc, described in the 'Giao Châu Ngoại Vực Ký' quoted in the 'Thủy Kinh Chú, ' a Chinese geography in the 6th century can be identified with the tidal irrigation system presently used in 'Thái Bình' province in the Red River Delta.
Part 1. From a comparison of this view with other opinions held by Vietnamese and French historians or geographers, and an analysis of the geographical situation and historical background of the tidal irrigation system in 'Thái Bình' province, it is evident that the basis of this view is a misinterpretation of French geographer P. Gourou's information on that irrigation system, and it is impossible to conclude that this system was used in the ancient Red River Delta.
Part 2. With identification of the Red River's names in the 'Thủy Kinh Chú' with present Red River Delta geography, indicates that 'Giao Chỉ' province in the 'Hán' Dynasty, which was composed of 10 or 12 counties, was bounded by the mountain area of 'Vinh Yên' and 'Bắc Giang' provinces in the west, the 'Phủ Lý' River-'Khoái Châu'-Sept Pagodes line on the south and the 'Đông Triẽu' mountains in the east. Counties were not established in the lower delta or the 'Thái Bình' Delta.
Part 3. Analysis of ethnographical and archeological data suggests that the reclamation in Red River Delta was accomplished by the introduction of the planting complex of fifth-month rice, tenthmonth rice and Aus-type rice, the first and last planted in lower-lying ricefields, for example in the backswamp, before the flood season, and the second planted mostly at higher places, such as hillsides, terraces and natural levees to avoid flooding. Furthermore, in the eastern part of 'Bắc Ninh' province, where until the 19th century, the lower ricefields were frequently influenced by tidal movement, rice varieties highly resistant to salt were probably introduced on the mud flat of the river beach. The cultivation of these tidal areas might have attracted the attention of Chinese travellers.
Part 4. A comparison of the description of 'Lạc Điẽn' and the tidal areas in 'Giao Châu Ngọai Vực Ký' with the 'Nam Việt Chí' quoted in 'Tháì Binh Quảng Ký' suggests that the identification of 'Lạc Điẽn' with the tidal areas is a forced analogy to explain the meaning of 'Lạc' as the ethnic name of old Vietnamese.
In conclusion, the cultivation of the ancient Red River Delta involved not engineering method, but agronomic farming, so that basis of the ancient 'Lạc Tướng' or Generals of 'Lạc' and 'Lạc Vướng' or king of 'Lạc' must lie in other factors than the control of a tidal irrigation system.
