Armed with machetes and chainsaws, hacking through fallen trees and wading through thick underbrush, the archaeologists cleared a path along rocky paths.
Finally, they reached their destination in Mexico’s Yucatan Peninsula: a hidden city where pyramids and palaces rose above crowds more than 1,000 years ago, with a ball court and terraces now buried and overgrown.
National Institute of Anthropology and History of Mexico saluted their work late last month, saying they had discovered an ancient Mayan city in a “vast area virtually unknown to archaeology.”
“These stories about ‘lost cities in the jungle’ – very often these things are quite minor or originated 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 discovered the ruins named them Ocomtún, using the Yucatec Maya word for the stone pillars found around the ancient city.
The Mexican institute described the site, in Campeche State, as having once been an important center of Maya life. During at least part of the Classic Maya era – around 250 to 900 AD – it was a well-populated area. Today it is part of a large ecological preserve where vines and tropical trees snarl at boots and tires, and fresh water slides through the porous limestone terrain.
“I’m often asked why no one has come there, and I say, ‘Well, probably because you have to be a little crazy to go there,'” said Ivan Sprajc, the survey’s lead archaeologist and a professor at a Slovenian research center. ZRC SAZU. “It’s not an easy job.”
The work has been revolutionized over the last decade by lidar, a technology that uses airborne lasers to pierce dense vegetation and reveal the ancient structures and human-altered landscapes below. But in the end, it still comes down to strenuous hikes.
“Sprajc is doing exactly the right thing; using lidar as a survey instrument but not interpreting the results without ground truthing,” said Rosemary Joyce, an anthropologist at the University of California, Berkeley.
She said in an email that it’s unlikely for any newly documented site to “materially change historical narratives,” but that such work could help researchers see “more variation in the ways different Maya communities lived during the Classic period.”
And it remains “unusual to find such a large site that no one knows about,” said Scott Hutson, an archaeologist at the University of Kentucky.
For decades archaeologists have relied on the help of descendants of the Maya to identify and excavate the ancient sites known to them. But because this part of Campeche has been a preserve for decades, Dr. Hutson said, “there have been no archaeologists walking through this area at all.”
Dr. Martin called the region a “void zone” on archaeologists’ maps.
Dr. Sprajc, 67, said the expedition to Ocomtún lasted about a month and a half, “relatively short” compared to the usual two months or more. The trip was made during the dry season, which can be scary – but less so than long treks in the rainy season.
Surrounded by wetlands, Ocomtún includes pyramids, plazas, elite residences and “strange” complexes of structures arranged almost in concentric circles, Dr. Sprajc said. “We don’t know anything about it from the rest of the Maya lowlands,” he said.
The largest documented structure in Ocomtún was a pyramid about 50 feet tall, which Dr. Sprajc said would have been a temple. It and some other structures stood on a large rectangular platform, raised about 30 feet from the ground and with sides more than 250 feet long.
“Just by the scale of it, the location of it, it must be a significant site,” said Charles Golden, an anthropologist at Brandeis University. He said excavations could help answer many questions about who lived there and their relationship to other Mayan cities and settlements.
People appeared to have abandoned Ocomtún around the same time they did other Maya cities, from about 800 to 1000 AD, a decline that researchers attribute to factors such as drought and political turmoil.
A hint to those conflicts may have been found at the site. While most of the structures were unadorned the team found, upside down in a stairwell, block with hieroglyphs this appears to have been from another Maya settlement.
Such monuments were sometimes “brought as spoils of war from other places, and this is what appears to have happened in this case,” said Dr. Sprajc.
Dr. Joyce said that the images of the block of conquest were normal, “so we may have evidence here of Ocomtún being part of the great wars that swirled around the main powers” of the Mayan world.
The team also found some agricultural terraces, which archaeologists called a sign of the Mayans’ widespread modifications to make the difficult environment more abundant for humans. By using hydraulics, water conservation and capture, and landscape engineering such as terraces, the Maya managed to live in “what seems like pretty inhospitable places today,” Dr. Martin said.
For modern groups passing through, water must be transported by truck. Dr. Sprajc said that even after his team cut about 37 miles of drivable road to Ocomtún, it took five to 10 hours to reach the site because the terrain was so difficult to traverse.
Such expeditions require huge expenses, both for the field work and before anyone sets foot in the forest. Lidar scans alone can cost tens of thousands of dollars. Dr. Sprajc found funding not only from his own institutionbut also four Slovenian companies and two American charities: the publisher Založba Rokus Klettthe railway service Adria combithe credit company Kreditna družba Ljubljanathe tourist company TO Ars Longathe Ken & Julie Jones Charitable Foundation and the Milwaukee Audubon Society.
Other researchers may now seek the funding, permits and supplies needed to excavate Ocomtún, but Dr. Sprajc will not be among them. He said he is busy planning a new expedition, next March or April, headed for another part of the Yucatan, where lidar images have shown leads.
Fellow scientists, supported by the work at Ocomtún, are looking forward to what his team might find next.
“This shows in places like Campeche, which on the one hand are quite close to places like Cancún and heavy tourist spots, there are still these places that no one has really documented,” said Dr. Golden, the Brandeis anthropologist. “So it’s always exciting that these places still have secrets to give.”