BY GUY GUGLIOTTA
 Washington Post Service

 The majestic pyramids of Teotihuacan were built high in the Valley of Mexico
 2000 years ago by a nameless people who dominated Mesoamerica for hundreds
 of years, only to disappear virtually without a trace between 600 and 700 A.D.

 The Teotihuacanos' origin, the structure of their government, the reasons for their
 demise and the very nature of their society remain largely a mystery, as
 tantalizing to modern archaeologists as to the Aztecs who inherited their
 monuments, but never knew who built them.

 Archaeologists recently discovered a previously unknown tomb and four skeletons
 inside Teotihuacan's Pyramid of the Moon, a find that should help dispel some of
 the fog, buttressing earlier hypotheses that the people of the pyramids had a
 strong militaristic and hierarchical bent. But, like earlier discoveries, the dig is
 missing an important element: There are no leaders.

 The new skeletons, like those from earlier finds, have their hands tied behind their
 backs. They were captives, servants, stand-ins, soldiers -- underlings of some
 sort, all 15 to 20 years old.

 ``We have never found evidence of any kind of governor or important person, in
 contrast to the Mayas or Aztecs, where we know the leader's name, when he
 lived and when he died,'' said Saburo Sugiyama, co-leader of the dig with Ruben
 Cabrera of Mexico's National Institute of Anthropology and History. ``We don't
 know anything because there is no written history.''

 RESEARCHERS FEELING THEIR WAY

 Indeed, while analysts at Teotihuacan have found ``well over 100 symbols that
 have some kind of standard significance,'' Arizona State archaeologist George
 Cowgill said, ``we still don't know if they have phonetic value.''

 In the absence of a written record, researchers are left to feel their way.
 Sugiyama, an archaeologist at Japan's Aichi Prefectural University and an adjunct
 professor at Arizona State University, compared the dig to a 1988 excavation he
 and Cabrera made at the Feathered Serpent Pyramid, at the other end of the
 broad avenue known as the Street of the Dead.

 Both sites are dated around 200 A.D. Both included green obsidian arrowheads
 and knives, as well as greenstone figurines, nose rings, earrings and ``butterfly
 necklaces.''

 Sugiyama found 133 skeletons in the Feathered Serpent Pyramid, all with tied
 hands, but he also found an abandoned tunnel and an open pit deep within the
 pyramid, suggesting that looters may have emptied a leader's grave.

 ``The intent'' in the Pyramid of the Moon excavation was to substantiate this
 theory by ``finding a royal burial or high-ranking burial'' intact, said Rene Millon, a
 retired University of Rochester archaeologist who mapped Teotihuacan in the
 1960s. Once again, it did not happen.

 The new dig did, however, unearth the bones of large felines, canines and
 predatory birds, Millon said, all symbols of military orders in Mesoamerica, and a
 further indication that Teotihuacan was a highly regimented and hierarchical
 society.

 NO ROYALTY BURIED IN PYRAMID

 Last year in an older section of the Pyramid of the Moon, Sugiyama found a tomb
 with a single male skeleton with bound hands, accompanied by a wooden cage
 with jaguar bones inside, an indication that the animal had been buried alive.

 Still, although jaguars have been associated with Mesoamerican royalty for at
 least 2,000 years, royalty does not seem to be buried in the pyramid. ``One of the
 [unresolved] issues is whether this was a monarchical or highly centralized
 leadership with one person,'' Cowgill said. ``Or was it collective? Nobody's
 suggesting a democracy, but it may have been governed by an oligarchic elite.''

 Teotihuacan, 30 miles northeast of Mexico City, vies with Peru's Machu Picchu
 as the most popular pre-Columbian tourist attraction in Latin America. It sprawls
 over eight square miles, much of it buried beneath farms, highways, a Mexican
 military base and five modern-day towns. Only 10 percent of this ancient
 metropolis has been excavated.

 The heart of the site is the 50-yard-wide Street of the Dead, with the Pyramid of
 the Moon at the north end, the 212-foot Pyramid of the Sun halfway down the
 avenue on the east, and the Ciudadela, or Citadel, which includes the Feathered
 Serpent Pyramid, on the southeast corner.

 The Teotihuacan pyramids, like those throughout the Americas, are made of
 stones, debris and dirt, faced with stone sculpture. When their creators wanted a
 new structure, they simply piled dirt atop the old pyramid and refaced it. The
 pyramids grew like onions.

 Sugiyama probed the Pyramid of the Moon through an 85-foot east-west tunnel
 that cut through seven separate ``phases'' before reaching the original pyramid
 along the north-south axis.

 WORLD'S SIXTH LARGEST CITY

 The first three phases were ``very simple,'' he said, with the original phase --
 believed to be the oldest construction at Teotihuacan -- dating from the first
 century A.D. The male skeleton and jaguar cage were found in phase four, dated
 about 150 A.D.

 Once at the center of the pyramid, excavators turned north and dug for more than
 260 feet to phase five before unearthing the four skeletons.

 In its heyday, about 300 A.D., Teotihuacan was the world's sixth-largest city,
 bigger than Rome, and its influence reached deep into the jungles. Millon said
 Teotihuacanos founded a 400-year dynasty at the classic Mayan city of Copan.

 But it all fell apart sometime after 600 A.D. Archaeologists have found evidence of
 selective burning of public structures and other destruction, and agree that by 750
 A.D., Teotihuacan as a civilization had ceased to exist. But the ruins survived
 through the era of the Toltecs to the rise of the Aztecs and beyond. The Aztecs
 revered the ancient site and named some of the buildings -- the Pyramid of the
 Sun, the Pyramid of the Moon.

 And it was the Aztecs who called the city Teotihuacan, the Place of the Gods. No
 one knew what its inhabitants had called it.

                     Copyright 1999 Miami Herald