The Yiluo basin is the heartland of the origin of early states in China. Based on archaeological data from the ongoing Yiluo project, I construct a GIS based study detailing the carrying capacity, catchment productivity, population fluctuation and development of social complexity in the surveyed region from the Peiligang to the Erlitou period. The study demonstrates that, although increase of population coincided with the initiation of social complexity, it probably did not lead to it in any direct causal way. Instead, the growing population might have provided more opportunities for elites to manipulate different strategies to maintain power and establish a more complex social structure. The study employs two models to explain the initiation of social complexity: 1) the "tribute" model, 2) the "special resources" model. Although there are some limitations in this study and some of the specific interpretations may change as more data and finer chronological controls become available, the analytical methods I employ here have shown great potential for application in future studies.
