Nearly five-and-a-half millennia ago, a bustling metropolis lay in the delta of the lower Yangtze, in what is now China’s Zhejiang province. You could enter on foot – there was a single road through the towering city walls – but most people travelled by boat via an intricate network of canals. At its heart was a massive palatial complex built on a platform of earth. There were huge granaries and cemeteries filled with elaborately decorated tombs, while the water system was controlled by an impressive series of dams and reservoirs. The inhabitants of this city, known today as Liangzhu, ruled the surrounding floodplains for nearly 1,000 years, their culture extending into the countryside for hundreds of kilometres. Then, around 4,300 years ago, the society quickly declined and its achievements were largely forgotten. It is only within the past decade that archaeologists have begun to reveal its true importance in world history. Their startling discoveries suggest that Liangzhu was eastern Asia’s oldest state-based society and its infrastructure may have surpassed those of Egypt and Mesopotamia, thousands of kilometres to the west. “There’s nothing in the world, from my vantage point, that is as monumental in terms of water management – or for that matter, any kind of management – that occurs so early in history,” says Vernon Scarborough, a professor of anthropology at the University of Cincinnati, in the United States. One of the biggest chapters in humanity’s story, the birth of civilisation, may need to be rewritten. The first evidence of a lost ancient culture in the Yangtze delta was uncovered in 1936, by Shi Xingeng, who worked at the West Lake Museum, in Hangzhou. He named the site Liangzhu, after a nearby town. However, the black pottery artefacts he found didn’t initially seem remarkable. It was only in the 1970s and 80s that Liangzhu began to generate much greater excitement, beginning with the excavation of some cemeteries in and around the ancient city. While many of the tombs were spartan, with few burial goods, some contained hundreds of beautiful jade objects, including the earliest examples of China’s iconic cong vessels and delicate bi discs. Many of these artefacts were engraved with the image of a man wearing an enormous plumed headdress, who appears to be riding a large, fanged monster – a motif that could represent a mythical or religious story. The graves also held ceremonial axes, pendants and plaques depicting the same mythical figures, which seem to have been attached to headgear. These kinds of objects had previously been assigned to much later periods, starting with the Zhou dynasty in 1046BC, but here they were, in a 5,000-year-old Neolithic burial place. It was the first sign that Liangzhu may have been a complex society, with workers producing costly and time-consuming artwork and a social elite rich enough to pay for it. Later digs revealed a huge earthen platform at the heart of the city. It is more than nine metres high and covers 300,000 square metres, and appears to have supported a palatial complex with buildings made of wood and bamboo, that the researchers named Mojiaoshan. Then came signs of city walls, more than 20 metres wide and often accompanied by internal and external moats. There was obviously an abundance of food, too: one pit in the city contains more than 10,000kgof burnt rice from a local granary. Then, in December 2017, a bombshell paper revealed the full extent of the society’s hydraulic engineering. Using a combination of satellite photography, coring and excavations, the team led by researchers at the Zhejiang Provincial Institute of Cultural Relics and Archaeology uncovered a series of low-lying levees built on swampy ground to control the flooding of the alluvial plain, and six “high dams” further upstream, creating reservoirs at the feet of the surrounding mountains. Together, the dams controlled the water flow over more than 10,000 hectares of land and were capable of holding back nearly 6.5 billion cubic metres of water. Carbon dating, along with an analysis of jade artefacts found near the levees, suggests that some of these dams were in operation 5,200 years ago, near the beginning of Liangzhu’s existence. And they were built to last: the Qiuwu dam is still in use. Besides allowing Liangzhu’s citizens to irrigate their paddy fields and control flooding after storm surges, the reservoirs fed 51 waterways. Made from natural river courses and artificial ditches, these canals were about 30km long in total. “Internal communication within the town must have been largely by boat; this was a town of canals as much as of roads,” noted archaeologist Colin Renfrew, at Britain’s University of Cambridge, and Liu Bin, director of the Zhejiang Provincial Institute of Cultural Relics and Archaeology, in a 2018 paper. Perhaps the closest comparison is medieval Venice or one of the “water towns” around Shanghai that emerged thousands of years after Liangzhu and that attract tourists to this day. The canal system was also used to transport building materials, including timber and rocks, down from the nearby mountains and into the city through its eight water gates. Foundations for the city walls, for instance, appear to come from mountains to the north. “These stones were not quarried per se using tools to cause physical breakage, but collected from the surface,” says Yijie Zhuang, a lecturer at University College London’s Institute of Archaeology and a co-author of the 2017 paper. While research in Liangzhu continues apace, discoveries elsewhere in China indicate that the civilisation’s rise was part of a broader social and cultural revolution. Recent archaeological studies show that, starting more than 5,000 years ago, many settlements were emerging in the lower and middle Yangtze regions, in what is now Sichuan province and along the lower Yellow River. Some, including Shijiahe in the middle Yangtze, are large enough to have required organised labour to build their moats and walls. “Liangzhu is by far the biggest, but you find other walled urban centres,” says Jessica Rawson, a professor of Chinese art and archaeology at Britain’s Oxford University. “And you get high levels of craftsmanship, not just in jade, but in several types of ceramics, in several parts of China.” There would have been communication between some of these sites, with the larger settlements acting as local power hubs. Liangzhu’s cultural influence, for instance, can be found in rural sites more than 100km away. This paints a very different picture from the traditional view of Chinese history. Small rice-farming communities began to appear around 10,000 years ago. Until recently, however, it was thought that the first Chinese state society – one with a formal political system and complex social organisation – emerged just 3,600 years ago, with the rise of the Shang dynasty in the Central Plains. But Liangzhu, far to the southeast, had many of the features of a state society around 1,700 years earlier, argue Renfrew and Liu, who has conducted much of the archaeological research at the site. First, there is the size of the population. Liu’s team estimates that this peaked at between 22,900 and 34,500, which is many times larger than any earlier Chinese community. Then there is clear evidence of a strict social hierarchy, such as the vast differences between the tombs of the rich and the poor. Finally, there is the ambition of the communal works, including the building of the city walls, the Mojiaoshan platform and palatial complex and the sophisticated hydraulic engineering. The construction work is particularly impressive considering the city’s inhabitants had no pack animals, such as horses or donkeys, or oxen to pull a plough, says Rawson. Nevertheless, they were able to relieve enough people from their agricultural duties to build these monumental structures. “Everything is dependent on human labour,” says Rawson. “And the key thing then is to organise that labour.” Liu’s team has estimated that constructing the dams alone would have required the movement of about 2.9 million cubic metres of earth, which would have taken 3,000 workers eight years to complete. This was a huge undertaking, of the kind that can only happen in a sophisticated society with central organisation and planning. “You can’t think of this hydraulic project without planning,” says Rawson. “This is not a small group of people – this is large-scale management.” Even on a global scale, Liangzhu’s waterworks were truly groundbreaking. The Middle East is often considered the cradle of civilisation, with a handful of urban societies, such as Tell Brak and Uruk in Mesopotamia, having emerged in the fourth millennium BC. These cities developed water-management technology, but their engineering did not match that of Liangzhu in size or complexity. [Liangzhu’s dams] may be the earliest communal works achieved anywhere in the world on such a scale As Liu and Renfrew put it: “[Liangzhu’s dams] may be the earliest communal works achieved anywhere in the world on such a scale.” Scarborough agrees. He visited the site in 2017 and was awestruck by how the citizens of Liangzhu had reshaped their environment. “It’s an engineered landscape that is second to none, given its antiquity,” he says. There is just one surprising absence at Liangzhu. So far, archaeologists have failed to find clear evidence of writing, which is sometimes considered a prerequisite of a fully formed state society. However, it is possible that some symbols found on the pottery and jade are not simply decorative. Zhang Chunfeng, a lecturer at the East China Normal University’s Department of Chinese Language and Literature, in Shanghai, says they have linguistic features. Some of the 656 symbols documented so far are highly standardised in form and many regularly appear across different sites at the same points on certain artefacts, such as the leg or mouth of a vessel. This suggests they may have a consistent meaning, like a label. Zhang also points to apparent rules in how certain symbols are constructed, which may have changed their meaning. These include the addition of new strokes and the systematic combination of different motifs, which again hints at a nascent writing system. “Some symbols have only decorative functions, some of them represent meaning and for some of them it is difficult to determine the function,” she says. Zhang hopes we may one day find the equivalent of a Rosetta Stone to decipher the symbols at Liangzhu. Even without one, the culture rivals other very early societies. With further research, Liangzhu might even shed light on the processes that led humanity to develop complex urban societies. The move from a hunter-gatherer to a farming lifestyle is one known force for the establishment of early settlements, as groups began to congregate around fields. Eventually, farmers pooled resources, collaboration and cooperation increased and communities grew. But what pushes a society to make the final leap to a large urban centre with more advanced technology, architecture and politics? Scarborough argues that environmental uncertainty played a central role in Liangzhu. This included the risk of flooding in the wet season and drier periods that would have destroyed the paddy fields. This uncertainty might first have encouraged the establishment of more regular religious practices that brought dispersed groups together for ceremonies. The depictions of a fearsome monster on artefacts across the region suggest the existence of some kind of shared mythology. Organised religious practices may, in turn, have encouraged the establishment of stricter social norms and even leadership roles for people who seemed able to predict or control the weather, for instance. The formation of a social hierarchy could then have helped to mobilise a large workforce for more practical communal projects such as dam building. While this would have brought greater cohesion and prosperity for the whole community, it would also have helped to cement the elite’s power by allowing them to control who had access to the technology and who could enter or leave the city by its canals. The result was a society with a formal government and with sufficient wealth to create elaborate artwork and architecture. Scarborough believes environmental uncertainty played a key role in the formation of civilisations in the Middle East, too – although the main threat there was drought. “It was more the re-routing of a limited amount of water off the Tigris or Euphrates to accommodate the sizeable cities that were beginning to spring up,” he says. In each case, the need to control the environment prompted greater cooperation and also gave power to an elite, promoting a new kind of social organisation. “Water [management] is not the only trigger for social complexity, but it’s certainly a primary one,” he says. If flooding was a trigger that set Liangzhu’s development in motion, it may also have been its downfall. Analysing layers of sediment in the region, Wang Zhanghua, a professor at the East China Normal University’s Institute of Estuarine and Coastal Research, and her colleagues found evidence of repeated marine flooding beginning around 4,500 years ago, with deposits of algae and small marine fossils directly on top of the layers associated with the Liangzhu culture. The damage caused by the flooding and the increased salinity would have made rice cultivation more and more difficult throughout the region, she says, undermining “the most important economic and social foundation of the Liangzhu society”. While the society itself collapsed, its influence appears to have lingered as the inhabitants moved to other parts of what is now China. Liu and others believe that elements of Liangzhu’s culture, such as the design of its jade congs , were borrowed and adopted by later societies. And the local landscape has forever been changed by the impressive hydraulic engineering. Flooding might have spelt the end of life in the city but its citizens left an indelible mark. And, with the ongoing archaeological excavations, this amazing culture is changing our ideas about the dawn of civilisation. Text: New Scientist Cradles of civilisation Discoveries in China point to a previously unknown civilisation in east Asia. How does Liangzhu measure up to other early human civilisations? To archaeologists, a civilisation is an urbanised state society with central settlements in the form of towns and cities, and complex social organisation, such as a class system or a ruling elite. Civilisations also have some control over the environment, so that people are more resistant to the whims of nature and can create a surplus of food that allows various industries to flourish. By-products of this way of living include writing, long-distance trade and monuments. The so-called Fertile Crescent east of the Mediterranean is often cited as “the cradle of civilisation”, thanks to the emergence of city-states such as Uruk, which became increasingly urbanised around 6,000 years ago. Estimates of Uruk’s population vary wildly, but, by around 4,900 years ago, it is thought to have been home to more than 60,000 people. Its communal works included temples and canals for irrigation. Uruk’s inhabitants invented the first known form of writing, cuneiform, and their texts include the earliest surviving great work of literature, The Epic of Gilgamesh , which tells of a legendary king of the city. At the western end of the Fertile Crescent, another civilisation was emerging at about the same time. Farming communities in Egypt also became increasingly urbanised and, by 5,100 years ago, they had coalesced into a society ruled from the city of Memphis by a pharaoh. This “first kingdom” employed the waters of the Nile for irrigation and boasted elaborate tombs – although not yet as ambitious as the famous pyramids – and a rudimentary writing system based on hieroglyphics. We now know that complex societies were developing independently elsewhere, though. The Indus valley in south Asia, for instance, became increasingly urbanised between 6,000 and 5,000 years ago, with the formation of cities such as Harappa, home to tens of thousands of people. Intriguingly, there seems to have been some communication and trade between the people of Harappa and Mesopotamia. It isn’t yet clear, however, whether the symbols found on Indus valley artefacts constituted a fully fledged writing system. The Liangzhu culture on the lower Yangtze had much in common with these early civilisations. With its social elite, skilled craftwork and refined architecture, it demonstrated the most important characteristics of a state society more than 5,000 years ago. Its population puts it on a scale similar to Uruk, Memphis and Harappa. And its communal works would have required large-scale social organisation and management. Liangzhu’s hydraulic system, which allowed its citizens to master their watery landscape, was so advanced that some consider it the most impressive anywhere in the world at that time. It is time to abandon the idea that civilisation had a single cradle.