Archaeologists have unearthed over 150 skulls in an empty field in Mexico, where a lake had once flown through.

The skulls date back between 600 and 850 A.D., and possibly belonged to victims of human sacrifice.

A team of researchers led by Christopher Morehart, an archaeologist at Georgia State University, used satellite images to map ancient canals and lakes that once surrounded the kingdom of Teotihuacan, some 30 miles away from Mexico City.

The research team examined a site at a drained lake, called Xaltocan, in the northern basin of Mexico. Earlier, the lake was surrounded by rural farmland.

During excavation, Morehart and his colleagues found more than 150 human skulls that were at least 1,100 years old. The skulls possessed just one or two vertebra attached, reports LiveScience. "It's absolutely remarkable to think about this little nothing on the landscape having potentially evidence of the largest mass human sacrifice in ancient Meso-America," Morehart said.

Most of the skulls belonged to males, showing that the victims were selectively chosen for the sacrifice, Destiny Crider, an archaeologist at Luther College in Iowa, who was not involved in the study, told LiveScience.

Besides the ancient skulls, researchers also discovered water-deity figurines, agricultural pottery and incense burners, suggesting a ritual purpose linked to local farming. Even after the sacrifices, people continued to conduct rituals at the spot. Later, when different people arrived at the area, they recognized the significance of the site. They did not continue with human sacrifices, but performed rituals, said the researchers.

Human sacrifices were known to be practiced throughout the region by the Teotihuacans and in the later Aztec empire. These rituals were thought to have been practiced in great pyramids within cities, and connected to state powers. But the discovery of human skulls in a small place, located several miles from the nearest major city of the day, has surprised the researchers. They believe the findings could change the notion about the ancient culture of the region.

The findings of the study appear in the journal of Latin American Antiquity.