Using phytolith analysis from a well-dated and high-resolution sediment sequence in the apex of northern Yangtze Delta, we investigate environmental changes, the rise and decline of rice exploitation and possible impacts of environment on rice exploitation during the early mid-Holocene. The phytolith sequence documents a relatively warm and dry interval during ca.9000 to 8200 cal yr BP, followed by climatic amelioration before 7200 cal yr BP. Phytolith evidence indicates that rice exploitation at the apex of northern Yangtze Delta began at 8200 cal yr BP, flourished by 7700 cal yr BP and ceased after 7400 cal yr BP. The first emergence of marine diatom species approximately 7300 cal yr BP likely indicates an accelerated sea-level rise. The apparent correlation of the initiation of rice exploitation with climatic amelioration during the early mid-Holocene suggests that climatic changes may have played an important role in facilitating rice exploitation. Both the ideal climatic conditions and stable sea level enabled flourishing rice exploitation during 8200 to 7400 cal yr BP. Although the climate remained warm and wet after 7400 cal yr BP, local sea-level rise possibly led to the termination of earlier rice exploitation at this site of the northern Yangtze Delta.

The large prehistoric city of Liangzhu and its associated earthen dike emerged on the Yangtze delta-coast after two millennia of occupation in this area by scattered communities. Details of its development have been widely discussed in the literature. Our results reveal that the city was selectively built at the head of an embayment backed by hills, with close access to food, freshwater and timber, and with protection from coastal hazards. Radiocarbon and optically stimulated luminescence (OSL) dating shows that it was built around 4.8–4.5 ka, and the earthen dike was constructed a little later at ~ 4.1 ka. During this time, saltwater wetlands were changing to freshwater in response to rapid coastal progradation as the postglacial sea-level rise stabilized. This facilitated rice farming and furthered the development of the city with elaborate city planning. The younger large-scale earthen dike and artificial ponds possibly suggest increasing demand for flood mitigation and irrigation.