Researchers using a high-tech aerial mapping technique have found tens of thousands of previously undetected Mayan houses, buildings, defence works and pyramids in the dense jungle of Guatemala's Peten region, suggesting that millions more people lived there than previously thought.

Key points: Laser mapping identified 60,000 individual structures including four major Mayan ceremonial centres with plazas and pyramids

Laser mapping identified 60,000 individual structures including four major Mayan ceremonial centres with plazas and pyramids 10 million people may have lived in the region — up to 3 times as many as previously believed

10 million people may have lived in the region — up to 3 times as many as previously believed Study identified industrial-sized agricultural fields and irrigation canals

The discoveries, which included industrial-sized agricultural fields and irrigation canals, were announced this week by an alliance of US, European and Guatemalan archaeologists working with Guatemala's Mayan Heritage and Nature Foundation.

The study estimates that roughly 10 million people may have lived within the Maya Lowlands, meaning that kind of massive food production might have been needed.

"That is two to three times more (inhabitants) than people were saying there were," said Marcello A Canuto, a professor of Anthropology at Tulane University in New Orleans.

Researchers used a mapping technique called LiDAR, which stands for Light Detection And Ranging.

It bounces pulsed laser light off the ground, revealing contours hidden by dense foliage.

The images revealed that the Mayans altered the landscape in a much broader way than previously thought; in some areas, 95 per cent of available land was cultivated.

"Their agriculture is much more intensive and therefore sustainable than we thought, and they were cultivating every inch of the land," said Francisco Estrada-Belli, a research assistant professor at Tulane University, noting the ancient Mayas partly drained swampy areas that haven't been considered worth farming since.

And the extensive defensive fences, ditch-and-rampart systems and irrigation canals suggest a highly organised workforce.

"There's state involvement here, because we see large canals being dug that are re-directing natural water flows," said Thomas Garrison, Assistant Professor of Anthropology at Ithaca College in New York.

The 2,100 square kilometres of mapping detected about 60,000 individual structures, including four major Mayan ceremonial centres with plazas and pyramids.

The Maya culture flourished between roughly 1,000 BCE and 900 CE.

Their descendants still live in the region.

This buried temple was already known to scientists, but thousands of others had been concealed by the jungle. ( Wikimedia Commons: Geoff Gallice )

Dense jungle

Mr Garrison said that this year he went to the field with the LiDAR data to look for one of the roads revealed.

"I found it, but if I had not had the LiDAR and known that that's what it was, I would have walked right over it, because of how dense the jungle is," he said.

Mr Garrison noted that unlike some other ancient cultures, whose fields, roads and outbuildings have been destroyed by subsequent generations of farming, the jungle grew over abandoned Maya fields and structures, both hiding and preserving them.

"The jungle, which has hindered us in our discovery efforts for so long, has actually worked as this great preservative tool of the impact the culture had across the landscape," said Mr Garrison, who worked on the project and specializes in the city of El Zotz, near Tikal.

LiDAR revealed a previously undetected structure between the two sites that Mr Garrison says "can't be called anything other than a Maya fortress".

"It's this hill-top citadel that has these ditch and rampart systems … when I went there, one of these things is nine meters tall," he noted.

In a way, the structures were hiding in plain sight.

"As soon as we saw this we all felt a little sheepish," Mr Canuto said of the LiDAR images, "because these were things that we had been walking over all the time."

The ruins at Tikal, discovered in the 19th century, are in the Peten region. ( Flickr: Phil )

AP