The early settlers probably came to Piedras Negras around 400 B.C., before the start of the Maya period, and established farms in the fertile valley. The archaeologists have found ceramics dating back to that time.
The site exploded in size far later, around 400 A.D., when many of the temples were built and the kingship may have been introduced.
A visitor entering from the river would have first seen the red-painted royal palace rising several stories, partly obscured by a haze of burning incense. "You would have smelled the city before coming close to it," Houston said.
But unlike many Maya reconstructions, which depict the cities as shining, well-maintained settlements, Piedras Negras was probably in a constant state of disrepair. It went through two major construction phases. First, mortuary pyramids containing the tombs of early kings were built. Then, around 700 A.D., the city was almost covered in masonry.
Like in many ancient cities, the population remained small. Even at its peak, Piedras Negras probably never had more than 5,000 residents.
The Maya kings were not only executive rulers, but also considered sacred, responsible for rituals such as bloodlettings and incense burnings. In the late classic Maya periodfrom 550 to 800 A.D.a clear pattern emerges where the rulers were succeeded by their sons. This is also when the palace, or "the Acropolis," a vast, sprawling set of patios and courtyards, becomes more inaccessible to the public.
"You get a feeling of social exclusivity in later dynasties," said Houston. "The very feeling of kingship changes, and it's expressed in the changing buildings of the site."
The dynasty is rocked when the line of succession breaks and several brothers seem to succeed one another as king. There are even hints of an abdication. Finally, the last known king is kidnapped by a neighboring kingdom.
"It looks like a great deal of violence took place in the royal palace," Houston said. "We're finding shattered buildings and shattered monuments."
Without the king, the royal palace soon begins to fill with squattersdebris and trash. Within a generation or two, most people abandon the city.
"Piedras Negras shows us how Mayan cities were built around their kings," said Houston. "When the kings thrive, so does the city. When the kings are taken out of commission, the cities also seem to wither and die."
The End of the Maya
The sudden demise of the Maya civilization is one of the greater archaeological mysteries of our time. There are several competing theories explaining the collapse, with some experts pointing to overpopulation, while others suggest environmental degradation and deforestation.
One of the most popular theories argues that a long period of dry climate, punctuated by three intense droughts, caused the end of the Maya.
Houston, however, doesn't agree with the drought theory.
"We do know that a lot of these cities had extreme difficulty around this time and maybe this had something to do with diminished rainfall," he said.
"But the fact is that Piedras Negras runs along a river that was never dry. They would always have had water to maintain their agricultural base."
He says there is no evidence of widespread massacres or rampant disease. Instead, he believes, the collapse began when people lost faith in the hierarchy.
"We do have evidence that points to a lot of turbulence and difficulties among those who were organizing the city and helping to run it as a collective entity," said Houston. "In the end, people simply voted with their feet. They didn't find Piedras Negras such a good place to live, so they left."
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