Archaeologists announced this week that they had discovered an extraordinary trove of well-preserved Mayan artifacts under the ancient city of Chichén Itzá in Mexico’s Yucatán Peninsula.
The artifacts were found in a cave called Balamkú, less than two miles from the famed pyramid known as the Temple of Kukulcan, or The Castle, which sits in the center of the site.
Guillermo de Anda, an investigator with the National Institute of Anthropology and History, said in a statement on Monday that the remarkable discovery could help researchers rewrite the history of Chichén Itzá, which flourished from roughly 750 to 1200 A.D.
The city was built on top of a network of waterways, including sinkholes called cenotes, which the ancient Mayans believed were sacred places that provided a portal to the underworld. Its name is sometimes translated as “the mouth of the well of the Itza,” the name of the main ethnic group in the area at the time.
Mr. De Anda and his colleagues were exploring that system of waterways when they found the artifacts, which date to around 700 to 1000 A.D., about 80 feet underground. The team has explored about 1,500 feet so far, crawling between various chambers connected by narrow tunnels.
“The place is extraordinary,” Mr. de Anda said in a video produced by the institute, speaking as he crawled through a dark, narrow passageway.
“Now comes a stage of documentation, protection and conservation of this marvelous and unique place.”
Local residents told the authorities about the cave more than five decades ago, but it was not studied extensively at the time, the institute said in its statement. Instead, the archaeologist Víctor Segovia Pinto ordered the entrance to be sealed, ensuring that its contents remained undisturbed. Last year, Luis Un, 68, who as a child was among the residents who had told officials about the cave, led Mr. de Anda’s team to its entrance again.
There are at least 200 artifacts, including fragments, ceramic incense holders, containers used to grind food and other items. Researchers expect that tests will show that they contain jade and remnants of seeds and bone that were used as offerings and have been found at similar sites.
Some of the incense holders bear the likeness of Tlaloc, the rain god of Central Mexico, who at some point “traveled” to the Yucatán. That could help researchers understand how the relationships between the Mayans and other civilizations evolved over time. The quantity of the artifacts and their placement in hard-to-reach parts of the cave could also indicate the site’s importance.
Mr. de Anda, who is also the director of the Great Maya Aquifer Project, said the discovery would allow researchers to develop new models of cave archaeology using 3-D mapping and modeling techniques.
Mr. de Anda and the project’s co-director, James Brady, a professor of Maya archaeologist at California State University, Los Angeles, said it was the most significant discovery in the area since the nearby cave of Balamkanché was found in the 1950s.
In a phone interview, Dr. Brady said that the artifacts at Balamkanché, many of which are similar to those found at Balamkú, were not closely studied because of a rush to develop the cave into a tourist site. He added that the findings indicated that subterranean spaces were more central to life in Chichén Itzá than previously recognized.
“We are just moving very slowly as we approach this, to make sure everything is done correctly,” Dr. Brady said.