A team of archaeologists has discovered more than 6,000 ancient Mayan structures hidden by vegetation in the southeastern Mexican state of Campeche, including a city of pyramids they have dubbed "Valeriana."

The city was discovered by chance thanks to Lidar, or light detection and ranging, a technology that uses lasers to map and analyze archaeological landscapes.

The dataset used for the study came from about 122 square kilometers of high-quality airborne Lidar data collected in 2013 as part of a forest monitoring project called Alianza, which aims to reduce emissions from deforestation and forest degradation.

When researchers processed the data using archaeological methods, they saw what others had missed: A huge ancient city that may have housed between 30,000 and 50,000 people at its peak between 750 and 850 AD.

What do researchers say?

"Our analysis revealed not only a picture of a densely settled region, but also a lot of variability," said the study's lead author, Luke Auld-Thomas of Northern Arizona University, in a press release.

"Not only did we find rural areas and smaller settlements, we also found a large city with pyramids right next to the only road in the area, near a village where people have been actively farming among the ruins for years," Auld-Thomas said.

The researcher noted that "there is much more to be discovered" in the so-called Central Maya Lowlands, a region in the southern part of the Yucatan Peninsula that includes parts of present-day Guatemala, Belize and the Mexican states of Campeche and Quintana Roo.

In recent years, Lidar has become a powerful tool in the archaeologist's arsenal, capable of documenting entire landscapes in minute detail, even under dense forest cover.

What is special about Valeriana?

Valeriana may be the most important Maya archaeological site by number of structures after Calakmul, which is considered the largest in Latin America.

Lidar technology revealed a sprawling, urban settlement, replete with architectural marvels and agricultural infrastructure. The analysis of the archaeological site yielded an aggregate settlement density of 55.3 structures per square kilometer. The researchers identified a total of 6,764 structures.

The area of Campeche, where the study was conducted, is characterized by tropical forests, limestone plains and seasonal wetlands and was a center of the ancient Maya civilization, especially during the Classic Period.

The Classic Maya civilization dates back to the period between 250 and 900 AD, when it extended its dominion over what is now southern Mexico and what is now Belize, El Salvador, Guatemala and Honduras.

dh/nm (Reuters, EFE)