Our data on the local population between Wu Xing's project and the later tenth century are spotty. Soon after the mid-eighth century census that is referenced in Chapter 4 provided the first somewhat credible count of registered households in greater Quanzhou, however, the northern core of the empire was wracked by the rebellion associated with An Lushan. This prompted a major wave of migration toward the comparative safety of the South, which remained largely unaffected and relatively stable. It is reasonable, therefore, to assume that Wu Xing was prompted to undertake construction of the Distributed Blessings Retention Dam and drainage of the coastal salt marsh partially if not primarily in response to pressure for land that was a result of a growing presence of the agriculturally oriented Sinitic immigrants.

That presence is attested by the next trove of census data compiled in the latter half of the tenth century. By the turn of the tenth century, faced with a growing pattern of rebellion that culminated with an uprising in the 870s and 880s from which the dynasty was unable to recover, the Tang court had unraveled. In the power vacuum that followed a congeries of autonomous and mutually hostile regional warlords competed for power. When all had shaken out and the Tang court had been formally deposed early in the tenth century, the Tang realm was a divided world. From a base on the Central Plain, the old heartland of Sinitic power and cultural authority, one leader claimed to have inherited the mantle of the Tang mandate and proclaimed a new dynasty called Liang. Along the length of the Yangtze River basin and across the deeper South, however, the struggle to fill the vacuum led to seven autonomous courts, each claiming their own share of the imperial mandate. The narrative of the interregnum decades that followed is complex and largely not relevant to our discussion. After several decades of division, however, a new order began to emerge from the Central Plain. This was the Song dynasty.

The Song court, which claimed the imperial mandate in 960, inherited from the Latter Zhou, the last of the interregnum northern dynasties, a policy of imperial reintegration.