The political competition and warfare of the eighth and early ninth centuries appear to have nearly depopulated the Petexbatun and probably much of the Pasion region. In the Petexbatun the change could not be more dramatic: a half dozen major centers, many minor centers, and high levels of population were reduced to less than 10 percent of earlier levels within a little more than half a century (a. d. 760 to 830).
Such rapid and large-scale population reduction would have involved migration to other regions. Petexbatun warfare by the late eighth century required even defensive positioning and fortification of small hamlets and agricultural field systems (O’Mansky and Dunning, Chapter 5, this volume). Locations suitable for settlement were greatly reduced, and even those would have difficulty protecting their fields and water sources. Emigration elsewhere would have been the best option for Petexbatun populations after a. d. 760 and it appears to have been the option generally chosen.
It is notable that during this same period some regions elsewhere in Peten experienced radical and erratic population changes. While most of the Petexbatun was depopulated in the late eighth to early ninth centuries, some populations moved to the Seibal, Altar, and Punta de Chimino enclaves or farther afield to other lakeside and riverine loci. For example, up the Pasion River in the Cancuen region to the south, new residences were constmcted outside that site’s epicenter in areas that had previously been unoccupied alluvial farmlands (Barrientos et al. 2000). This occupation at Cancuen introduced distinctive middle Pasion ceramic modes and types, including Pantano and Chaquisite impressed in middens and imported Chablekal Fine Gray vessels in burials (Bill 2000; Bill and Callaghan 2001).
Meanwhile, farther downriver (north) on the Usumacinta system, Yaxchilan, Piedras Negras, and Palenque suffered decline or abandonment early in the ninth century. In part this probably was due to warfare and emigration, as in the lower Pasion. Note, however, that intensified warfare and the formation of the Seibal and Altar conquest states also had effectively blocked the Pasion/Usumacinta River trade artery and the highland/lowland exchange networks in obsidian, py-rite, jade, shell, and other exotics. The great river portage kingdoms of the west, including Cancuen, Yaxchilan, and Piedras Negras, would have been deprived of a major segment of their distribution and patronage networks. Composition and production studies have confirmed that in the Terminal Classic, long-distance exchange systems were disrupted (Foias and Bishop 1997; Foias 1996, 2004). Combined with intensified warfare and major military defeats, the loss of patronage networks may have driven the rapid decline of these western centers (Martin andGrube 2000: 116-175).
Some recent interpretations have attributed the decline at Piedras Negras and elsewhere to a failure of leadership to meet with expectations of “moral community” needed to retain population. With this failure of the ruler’s “moral authority” at Piedras, “the moral community, now inverted into a community of despair, would potentially transform itself into an expulsive force,” resulting in the emigration of its sustaining population (Houston et al. 2001; Sharer and Golden in press). Yet the decline at Piedras Negras, and later Yaxchilan and Palenque, can be more economically explained as an expected response by the population to historically recorded humiliating military defeats, political fragmentation, and the disruption of elite access to many exotics brought by the PasionAJsumacinta trade routes. Loss of faith in leadership and emigration elsewhere would be expected in kingdoms that could no longer provide physical security or prized exotics to their elite subordinates and the sustaining population. The pattern of abandonment at these great western centers of Piedras, Yaxchilan, and Palenque was perfectly consistent in nature and timing with the disruptions we have described here to the south and east on this same western river system during this same period (Demarest and Fahsen 2003).
Elsewhere in Peten, population increases in the late eighth century were sometimes accompanied by political fragmentation and a proliferation of Emblem Glyphs. In the northeast Peten and northern Belize the picture is complex and difficult to align with other regions. Adams et al. (see Chapter 15, this volume) record great population increases in some centers, while others decline or are abandoned. There, as in most of Peten, ceramic chronologies are less refined than in the Petexbatun, and so difficult to align for processual or culture-historical interpretation. Still, the general late-eighth-century picture throughout central Peten, Belize, and to the north in the Puuc zone appears to reflect population increases, but in an irregular pattern, accompanied by political disruptions and re-entrenchment (e. g., Dunning 1992; Chapters 14-21, this volume). In my view, this highly variable pattern does not correspond to the great “collapse” expected from drought/fam-ine models, especially given that Belize as a whole maintains large populations into the Postclassic period.
Ceramic markers for Tepeu 3 in many areas are dependent upon the presence of types or traits from the lower Pasion region. In addition to trade, migration to the east of small groups and families, as well as migrations along the Pasion itself, could explain both the general spread of Pasion ceramic markers to the east and north and the changes upriver to the south at Cancuen. Rapid population growth in some regions in the eighth century also might, in part, reflect the direct or indirect impact of gradual immigration from the west. As indicated by Ashmore et al. (Chapter 14, this volume), agriculturally rich areas in Belize may have attracted families and small groups from the depopulating kingdoms of central and western Peten. We can speculate that the stresses associated with overpopulation in late Tepeu 2 times would have been exacerbated by such population displacements, even if the units involved were very small. Migration might also have contributed to the political disruptions, re-entrenchment, and transformations taking place in other regions. As we know from many modem examples, immigration can be positive or negative in its effect, depending on the nature and timing of movements, and especially on economic, ecological, and political conditions of the region receiving migrants.