"The discovery constitutes the first architectural evidence of such an early occupation of the ancient Mayan cities of the Upper Usumacinta basin" in the Lacandona Jungle, the National Institute of Anthropology and History said in a statement Wednesday.
The project's director, Luis Alberto Martos, said this new discovery was made in a sunken courtyard located in the northern part of the the Plan de Ayutla archaeological site and represents the first evidence of occupation of that area between 50 BC and 50 AD.
Martos added that the earliest concrete evidence of Mayan occupation of that region before now had dated back only to 250 AD.
He said the palace consists of "rooms with walls almost one meter wide, whose corners are rounded, an early characteristic of Mayan architecture".
The archaeologist added that Mayans of a later era dismantled the palace and filled in the courtyard to raise the level of the other buildings, and that is why "the remains of the early palace remained below and were preserved".
The later constructions were built between 250-800 AD and correspond to the Classic period, when this site played an important political role.
This research will provide a deeper look at political interaction and integration in this region, "an area where several kingdoms were in conflict and battles were waged and alliances formed", Martos said.