| Abstract: |
Much of Yunnans limited flat land is around the Dian Lakes. The levels of these lakes seem to have fluctuated over many metres through the millennia, and this has resulted in alterations to the extent and depth of water, the extent of surrounding flat land, and to that of land enriched by floods. Appreciating these changes could provide pointers to aspects of the cultures surrounding these lakes. First, the discovery of the occupation site near Wangjiadun, 3 to 5 metres below the current level of Dianchi Lake, indicates that the lake could have been smaller and shallower than today. From the dates and depths of cored samples, it would seem that the this habitation could have been occupied more than 4,500 years ago, and not in the early Bronze Age as has been suggested. Second, historical records indicate that the Dian kingdom was situated on thousands of square li of rich flat land around Dianchi Lake. However, through use of a digital elevation model of the area, it is determined that this area was about 800 li<sup>2</sup>substantially less. Even if the other major Dian LakesFuxian, Xingyun and Qi Luare included, the total area could only be about 1,000 li<sup>2</sup>. This limited area of fertile land suggests that other sources of wealth, such as trade and minerals, played a greater role, and that the population was relatively small. This calls into question the nature of the socio-political structure within the Dian culture. Third, another inference from the historical record is that accelerated soil erosion resulted in the blocking of the outlet of Dianchi Lake, starting in the 13th century. This caused extensive flooding, even around Kunming. However, hydraulic considerations suggest that erosion could not have been the cause
instead, the flooding may have been induced by some other human activity.
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