Researchers using a high-tech aerial mapping technique have found tens of thousands of previously undetected Mayan houses, buildings, defence works and pyramids in dense jungle in Guatemala.
The discovery suggests millions more people lived at the Peten region site than previously thought.
The find, which includes industrial-sized agricultural fields and irrigation canals, was announced on Thursday by an alliance of US, European and Guatemalan archaeologists working with Guatemala's Mayan Heritage and Nature Foundation.
The study estimates 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.
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 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.
The ancient Mayas partly drained swampy areas that haven't been considered worth farming since, Estrada-Belli noted.
And the extensive defensive fences, ditch-and-rampart systems and irrigation canals suggest a highly organised workforce.
The 2,100 square kilometres of mapping done vastly expands the area that was intensively occupied by the Maya, whose culture flourished between roughly 1,000 BC and 900 AD.
Their descendants still live in the region.
The mapping detected about 60,000 individual structures, including four major Mayan ceremonial centres with plazas and pyramids.
