The ancient people of Tongatapu, the main island of Tonga, had a sophisticated ancient society with a keen eye for design. Using LiDAR, a team of researchers showed that as early as 300 AD, the island’s settlements featured a network of carefully designed roads and gardens, emphasizing green spaces and sustainability.

Compared to places like Europe or Asia, we know very little about how people built cities in the Pacific — and cities can be built in very different ways. From the moving settlements of the Mongolian hordes to the thriving ancient Romans and the megacities of China, different cultures have shown a lot of variety in urban design. But all cities have something in common.

“When groups of people come together to live in larger groups,” the authors of the new study write, “they experience similar challenges in deciding where they will locate the growing populations and how they will manage increasing social interactions.”

The people of Tongatapu also faced this type of dilemma, but the solutions they came up with were different.

Pacific cities are older than we thought

When Europeans first discovered Tongatapu in 1643, they came across a strikingly complex settlement. The famous Captain James Cook, in 1773, wrote extensively on the impressive transportation that served the island. But this system wasn’t new — it had been around for over a millennium.

“Earth structures were being constructed in Tongatapu around AD 300. This is 700 years earlier than previously thought,” said lead author Phillip Parton, from the Australian National University.  

Using LiDAR, the researchers mapped these settlements in detail and then dated their development.

LiDAR, or Light Detection and Ranging, is a remote sensing technology that uses laser light to measure distances and create precise, three-dimensional information about the shape of the Earth and its surface characteristics.

In archaeology, LiDAR is usually used to penetrate dense vegetation and provide high-resolution 3D images of the Earth’s surface, revealing hidden structures and landscape modifications made by ancient civilizations. The survey showed that, first of all, Pacific cities are much older than we thought. But that’s not all.

These cities were sparsely populated but highly organized. Unlike the dense urban sprawl associated with ancient cities in other parts of the world, Tongan settlements were spread out, incorporating large amounts of green and agricultural spaces within residential areas. This layout provided a unique form of urban efficiency and sustainability for the ancient world, supporting large populations without the crowding and sanitation issues faced by more densely built cities like Rome.

Europeans changed the system

The structures and layout of the built settlements also suggest advanced urban planning with complex social structures and institutions. The presence of structured, hierarchical societies was evident, with clear distinctions in settlement layouts that suggested organized social stratification and governance.

Roads, fortifications, and monumental architecture such as burial mounds and ceremonial spaces were all part of this urban landscape, pointing to a sophisticated society capable of large-scale architectural projects and community organization. Remarkably, this also fits with Cook’s description.

“As settlements grew, they had to come up with new ways of supporting that growing population. This kind of set-up — what we call low-density urbanization — sets in motion huge social and economic change. People are interacting more and doing different kinds of work,” Parton added.

This innovative way of designing cities lasted until European colonizers came in. When Europeans started colonizing the area, the old way of building cities collapsed — because of the Europeans.

“It didn’t collapse because the system was flawed; it had more to do with the arrival of Europeans and introduced diseases,” Parton said, adding that this type of research is just starting. “This is just the beginning in terms of early Pacific settlements. There’s likely still much to be discovered,” the researcher concludes.

The findings appeared in the Journal of Archaeological Method and Theory.