The probable E-Group assemblage was a primary focus of our investigation at the lowland Maya center of Ceibal. Tunnel excavation into Structure A-20 (the western structure of this complex) demonstrated that the Ceibal residents built the earliest version (Structure Ajaw) by carving natural marl around 950b.c.The earliest version of the eastern platform (Structure Xa'an) was also made at the same time out of the natural marl layer. Through a series of renovations, the western structure grew into a pyramidal shape, and later versions of the eastern platform were moved further to the east. In addition, excavations revealed numerous caches, many with greenstone axes, along the center line of the E-Group assemblage. These results show that a formal ceremonial complex was established at the beginning of occupation at Ceibal, and its construction and public events held there played an important role in the creation of a new community.

Excavations in large platforms in the center of Ceibal revealed extensive early Middle Preclassic constructions. They consisted of extensive clay platforms that supported low basal structural platforms. Although the function of the earliest platform, Sulul, during the Real-Xe 1 and 2 phases (950–775 b.c.) is not clear, the one built during the Real-Xe 3 phase (775–700 b.c.) likely supported multiple residential buildings. The emphasis on elevating this domestic space above the natural land surface and the communal labor involved in these constructions indicate that they were most likely inhabited by an emergent elite. These places were continuously remodeled and used until the end of the Middle Preclassic. This new data from Ceibal contributes significantly to our understanding of the processes involved in the transition to a sedentary lifestyle and the development of social and political differentiation in the Maya lowlands.

The lowland Maya site of Ceibal, Guatemala, had a long history of occupation, spanning from the Middle Preclassic Period through the Terminal Classic (1000 BC to AD 950). The Ceibal-Petexbatun Archaeological Project has been conducting archaeological investigations at this site since 2005 and has obtained 154 radiocarbon dates, which represent the largest collection of radiocarbon assays from a single Maya site. The Bayesian analysis of these dates, combined with a detailed study of ceramics, allowed us to develop a high-precision chronology for Ceibal. Through this chronology, we traced the trajectories of the Preclassic collapse around AD 150-300 and the Classic collapse around AD 800-950, revealing similar patterns in the two cases. Social instability started with the intensification of warfare around 75 BC and AD 735, respectively, followed by the fall of multiple centers across the Maya lowlands around AD 150 and 810. The population of Ceibal persisted for some time in both cases, but the center eventually experienced major decline around AD 300 and 900. Despite these similarities in their diachronic trajectories, the outcomes of these collapses were different, with the former associated with the development of dynasties centered on divine rulership and the latter leading to their downfalls. The Ceibal dynasty emerged during the period of low population after the Preclassic collapse, suggesting that this dynasty was placed under the influence from, or by the direct intervention of, an external power.Maya archaeology | political collapse | dynastic origins | radiocarbon dating | Bayesian statistics

Skeletal remains excavated from the lowland Maya site of Ceibal, representing approximately 117 individuals, provide significant data for the study of changes in bodily treatments and mortuary practices from 1000b.c.toa.d.900. The early Middle Preclassic residents of Ceibal apparently did not bury their dead inside residential structures, which represents a burial practice different from those found at contemporaneous Belizean sites. During this time, tabular erect cranial deformations were found among possible local residents. Sacrificial burials were present by the end of this period, but skeletal remains of violent rituals deposited in public spaces increased from the Middle Preclassic to the Late Preclassic. During the Late Preclassic, tabular erect cranial deformations coexisted with tabular oblique shapes. The Classic period witnessed a prevalence of tabular oblique forms, which were probably tied to local residents. The common placement of the dead under house floors and the preference of ceramic vessels as burial goods also indicate Ceibal's strong affinities with other parts of the Maya lowlands during the Late Classic period. During the Terminal Classic period, there was a resurgence in the placement of sacrificial burials in public spaces and tabular erect cranial deformations were found in possible non-local individuals.

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