It has been about forty years since I first encountered the tale of Wu Xing and his battle with the jiao as I was researching my doctoral dissertation. As I shall discuss, Wu was directing a major project to drain a coastal salt marsh on the central Fujian coast. Having completed his project, so the narrative goes, the dikes that channeled fresh water through the newly reclaimed land were attacked by a jiao. Wu swore he would rescue his project by killing the beast—and beast it was. Wu grabbed his sword and plunged into the water to battle. After three days the jiao and Wu were both dead. The drainage project, however, was saved and to this day remains the core of one of China's most productive rice regions.

I have long found the story intrinsically interesting for its own sake at several levels. Who, for example, was Wu Xing, and why did he undertake such a massive project? What was its impact on the regional ecology and economy? What became of the people who had lived with the marsh before Wu drained it? These are all questions that link to wider themes, as I shall explain. Ultimately, however, there is a question that lies at the center of Wu Xing's tale: What is a jiao? It is at the core of the story, as I shall explain, yet no such creature exists in the natural world. Why does the story depend on such a mythological creature? Or could it in fact be something real?

Even if readers share my sense that these are interesting questions, none would be of much significance if there were not those broader themes, if there were not a broader insight to extract. Wu Xing's project, I will suggest, is a micro-event that provides insight into the much larger process whereby the vast reaches of southern China, the land that is drained by the middle and lower reaches of the Yangtze River basin as well as the adjacent littoral regions that frame that basin, were folded into the larger framework that today is China. Long ago the South, as I shall call that vast area, was home to a wide array of local and regional cultures.