Piedras Negras seems to have been an independent city-state for most of the Classic Period, although sometimes in alliance with other states of the region and perhaps paying tribute to others at times. It had an alliance with Yaxchilan, some 40 km up river. Ceramics show the site was occupied from the mid 7th century BC to 850 AD. Its most impressive period of sculpture and architecture dated from about 608 through 810, although there is some evidence that Piedras Negras was already a city of some importance earlier. The artistry of the sculpture of the late classic period of Piedras Negras is considered particularly fine.
Before the site was abandoned, some monuments were deliberately damaged, including images and glyphs of rulers defaced, but images and glyphs of dieties left intact, suggesting a revolt or conquest by people literate in Maya writing.
Modern history of the site
The site was first explored, mapped, and its monuments photographed by Teoberto Maler at the end of the 19th century.
An archeological project at Piedras Negras was conducted by the University of Pennsylvania from 1931 to 1939. Further archeological work here was conducted from 1997 to 1999 by Instituto de Antropología e Historia de Guatemala (IDAEH).
Mayanist Tatiana Prouskourikoff was the first to decipher the names and dates of a Maya dynasty from her work with the monuments at this site. By her request, Prouskourikoff was buried here after he death.
In 2002 the World Monuments Fund earmarked 100,000 United States dollars for the conservation of Piedras Negras. It is today part of Guatemala's "Selva Lacandona" national park.