Archaeologists find a Maya city in a “blank area” of a map of Yucatan

Armed with machetes and chainsaws, cutting down fallen trees and wading through thick scrub, the archaeologists cleared a path down the rocky paths.

Finally, they reach their destination on Mexico’s Yucatan Peninsula: a hidden city where pyramids and palaces rose above the crowds more than 1,000 years ago, with a ball court and terraces now buried and overgrown.

Mexican National Institute of Anthropology and History praised their work late last month, saying they had discovered an ancient Maya city in “a vast area practically unknown to archeology.”

“These stories about ‘cities lost in the woods’—these are often very small things or are spun off by journalists,” said Simon Martin, a political anthropologist who was not involved in the work. “But this is much closer to the real deal.”

The team of archaeologists who unearthed the ruins named it Ocomtún, using the Yucatec Maya word for the stone pillars found around the ancient city.

The site, in the state of Campeche, has been described by the Mexican Institute as having once been a major center of Mayan life. During at least part of the Classic Maya era – around 250 to 900 AD – it was a populated area. Today it’s part of a large ecological reserve where vines and tropical trees snarl boots and tires, and fresh water slips through the porous limestone terrain.

“Often they ask me why no one has ever come there, and I say, ‘Well, maybe it’s because you need a few nuts to go there,’” said Ivan Sprajc, lead archaeologist on the survey and professor at the Slovenian Research Center. Sazu Zark. “It is not an easy task.”

Work has been revolutionized over the past decade by lidar, a technology that uses airborne lasers to cut through dense vegetation and reveal ancient structures and man-made landscapes below. But in the end, it’s still about trekking.

“Sprajc is doing precisely the right thing; using lidar as a survey tool but without interpreting the results without knowing the ground reality,” said Rosemary Joyce, an anthropologist at the University of California, Berkeley.

It’s unlikely that any newly documented site “materially alters historical accounts,” she said in an email, but such work could help researchers see “more variation in the ways different Maya societies carried out life during the Classic period.”

“It’s still very unusual to find such a large site that nobody knows about,” said Scott Hutson, an archaeologist at the University of Kentucky.

For decades, archaeologists have relied on the help of Maya descendants to locate and excavate ancient sites familiar to them. But because this part of Campeche has been protected for decades, Dr. Hutson said, “There simply have been no archaeologists ever walking into this area.”

Dr. Martin called the area a “blank zone” on archaeologists’ maps.

The expedition to Oakhamton took about a month and a half, said Dr. Sprajk, 67, “relatively short” compared to the usual two months or more. The trip took place during the dry season, which can be strenuous – but less so than the long trekking in the wet season.

Surrounded by wetlands, Dr. Sprajk said Oakcompton includes pyramids, plazas, refined dwellings, and “exotic” complexes of structures arranged roughly in concentric circles. “We don’t know anything about it from the rest of the Maya lowlands,” he said.

The largest documented structure at Ocomtún was a pyramid about 50 feet high, which Dr. Sprajc said could have been a temple. It stood with some other structures on a large oblong platform, about 30 feet off the ground and with sides more than 250 feet long.

“Just by its size, by its location, should it be an important site,” said Charles Golden, an anthropologist at Brandeis University. He said the excavations could help answer a host of questions about who lived there and their relationship to other Mayan cities and settlements.

People appear to have left Ocomtón around the same time they left other Maya cities, from about AD 800 to 1000, a decline that researchers attribute to factors such as drought and political strife.

A hint of those inconsistencies may have been found at the site. While most of the structures were undecorated the team found upside down in a ladder, Block with hieroglyphs which appears to have been from another Maya settlement.

Sometimes such relics were “brought in as spoils of war from other sites, and that seems to have been the case in this case,” Dr. Sprajk said.

The depictions of conquest were normal, Dr. Joyce said, “so we may have evidence here that Ocomtún is part of the great wars that took place over the major powers” in the Maya world.

The team also found some agricultural terraces, which archaeologists describe as a sign of widespread modifications in the Maya civilization to make the challenging environment more bountiful for humans. Dr. Martin said that with hydraulics, water conservation and capture, and landscaping like amphitheatres, she was able to live in “what today seem rather inhospitable regions.”

For recent groups passing by, water has to be hauled in by truck. Even after his team carved out some 37 miles of drivable trail to Ocomtún, Dr. Sprajc said, it took five to 10 hours to get to the site because of the difficult terrain.

Such expeditions required huge expenditures, both for field work and before anyone set foot in a forest. Lidar scans alone can cost tens of thousands of dollars. Dr. Sprajc found funding not only from his country institutionbut also four Slovenian companies and two American charities: the publisher Založba Rokus Klettrailway service Adria Combicredit company Kreditna družba LjubljanaTourism company Ars longaand the Kane and Julie Jones Charitable Foundation and Foundation Milwaukee Audubon Society.

Other researchers may now seek funding, permits, and supplies to excavate at Ocomtún, but Dr. Sprajc will not be among them. He said he was busy planning a new expedition, next March or April, heading to another part of the Yucatan where lidar images emerged as a flagship.

His fellow scientists, buoyed by the work at Ocomtún, are looking forward to what his team might find next.

“It shows in places like Campeche, which on the one hand are very close to places like Cancun and the busy tourist spots, there are still these places that no one really documents,” said Dr. Golden, an anthropologist at Brandeis. “So it’s always exciting that these places still have secrets to spill.”