The city of Liangzhu
A walled city of dams and jade, one of China's first states
In the Yangtze delta, around 3300–2300 BC, stood the walled city of Liangzhu, covering almost 3 km². Its people built a system of dams against floods and carved ritual jade bi discs and cong tubes. In 2019 the ruins were listed by UNESCO as evidence of an early state in China.