The team has excavated about 16,000 sq m, uncovering compelling evidence of a dual-layer defensive structure. Preliminary work has revealed an inner wall and moat, forming a neat, rounded-square enclosure covering nearly 75,000 sq m. Evidence points to a larger outer wall and a complex of three moats, suggesting the outer city spans 125,000 sq m. Carbon dating of artifacts from the moats confirms their construction to be around 6,000 years ago.

"The scale and complexity of the fortifications suggest a highly organized society with significant communal planning and labor coordination," Zhou says.

"The inner wall and moat are closed and intact, indicating a clear boundary for the core urban area, "Zhou says, adding the construction is sophisticated, with the walls built in multiple layers and supported by revetments.