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Maya UnderworldThe bones of six humans—including two children—jade beads, shells, and stone tools are among the Maya "treasures" recently found in a water-filled cave off a sinkhole at the famous archaeological site of Chichén Itzá (picture) in Mexico, archaeologists say. The ancient objects are most likely related to a ritual human sacrifice during a time when water levels were lower, sometime between A.D. 850 and 1250, the researchers say. It's "very improbable" that the remains and artifacts were "just tossed" into the sinkhole, known as a cenote, expedition leader Guillermo Anda told National Geographic News in an email. Rather, he said, they were likely placed there during a ceremony to appease the Maya rain god, Chaak.Extending from what is now southern Mexico through Guatemala and into northern Belize, the Maya Empire is noted for having the only known written language in Mesoamerica, as well as for its elaborate works of art and architecture. Chichén Itzá was one of the greatest Maya cities on Mexico's Yucatán Peninsula. (See an interactive map of key Maya sites.)The discovery of a human sacrifice deep in one the region's cenotes supports the idea that, for the Maya, the sinkholes "represented thresholds of communication with the spiritual and sacred world that lay under the surface of the Earth," said Anda, a professor at the Autonomous University of Yucatán.(See pictures of famous sinkholes around the world.)—John Roach

Photograph courtesy Tamara Thomsen