"For decades the tumi knife bearing an image of the Sican Deity has been a national symbol of Peru," Shimada said.
"Yet thus far all known tumi knives with such a representation had been illegally looted, and little was known of their cultural contexts."
Shimada said some scholars believe the deity on the knives to be Naylamp, a figure who, according to an oral history recorded by Spaniards in the 16th century, became a god after emerging from the sea.
Shimada said it is particularly important that the tomb complex was found beneath a pyramidal temple mound known as Huaca Loro.
"Many pre-Hispanic tombs were placed in existing mounds, but this is the first time that a major cemetery was found underlying a major mound," he said.
The artifacts and elements of the tombs' layout suggest that the Sican had a deep reverence for ancestors and that the people had apparently made repeated pilgrimages to the site.
"The fact that people had come at least 20 times over 500 years to leave offerings and burn the ground around the cemetery indicates the intimate and persistent relations between local populations and their ancestors," according to the project summary.
Shimada said the team found a "seated adult male personage wearing a copper-silver crown, decorated tumi knives, a gilt copper ceremonial cup, a large pectoral made of a gilt copper disk, and turquoise, shell, and other beads."
The man was found in a small square tomb 23 feet (7 meters) below the modern ground surface. He had been buried facing east toward a tomb believed to house one of the Sican's dynastic founders. "We also documented a number of large tombs of female elites that suggest that they played important social and religious roles in the Middle Sican culture," Shimada said.
One woman in her 20s was found sitting cross-legged in a 11.5-foot-square (3.5-meter-square) shaft tomb 33 feet (10 meters) below the surface.
Her body was surrounded by painted cloths and flanked by ceramic vessels, cast bronze artifacts, and a ceremonial cup of copper-silver alloy, he said.
"Overwhelmingly Important" Find
Joanne Pillsbury, director of pre-Columbian studies at the Dumbarton Oaks Research Library in Washington, D.C., said the discovery was "very exciting" and that she expected it to generate "important new data on this complex pre-Inca culture.
"This excavation is a rare opportunity to examine the contents of an intricate burial," she said.
She added that Shimada will likely produce insights into ancient health and cultural affiliations by analyzing skeletal materials found at the site.
Walter Alva, a Peruvian anthropologist, has also praised the discovery, telling the Associated Press it was "overwhelmingly important."
Shimada has received funding in the past from the National Geographic Society's Committee for Research and Exploration, including the excavation of a Middle Sican pottery workshop in 2001.
National Geographic News is a division of the National Geographic Society.
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