Aquatic landscape and the emergence of walled sites in late Neolithic Central Plains of China: Integrating archaeological and geoarchaeological evidence from the Guchengzhai site

The emergence of many late-Neolithic and early Bronze-Age walled sites on China's Central Plains coincided with some prominent Holocene climate events. Recent excavation and geoarchaeological investigation at one of the largest walled sites of Guchengzhai provide important data to examine some of the questions concerning the long-term relationship between the formation of aquatic landscape and social evolution in late prehistoric Central Plains. We collected fine-grained paleo-environmental and archaeological evidence from a range of on- and off-site contexts to reconstruct the late-Holocene paleo-environment surrounding the walled site, and examine the construction, maintenance and abandonment processes of its large-size moat. Our results show that there existed many small-to-large-sized waterbodies during the late Holocene, which, together with local rivers, were the main source of water to the site. The Guchengzhai population was drawn to the low-lying land near the river and other waterbodies with an optimal hydrological condition. During its use, the moat might have been linked to the nearby wetlands and/or rivers. The hydrological regime was dominated by gentle but relatively sediment-laden flow, being punctuated by several high-energy flood events. The sedimentation of light yellowish silt and sand with some anthropogenic inclusions during the use of the moat gave way to a quick siltation with the deposition of rich organic matter when the moat ceased to function as a main channel for water flow, although other land-use activities such as fire (land clearance?) continued to occur in the vicinity. The reconstructed ‘life-history’ of the moat demonstrates the increasingly acute challenge facing the growing population living at Guchengzhai as the climate was becoming drier. The construction and operation of the moat signified technological innovations and intensified water management at Guchengzhai, which led to the formation of distinctive aquatic landscape that featured large-scale hydraulic infrastructures in a hydrologically optimal environment. We contend that such was a common characteristic or trend shared by many contemporary or later-period walled sites on the Central Plains.