The American Southwest is often considered, archaeologically, a peripheral area on the fringes of the large and important Mesoamerican culture area to the south, and while this view was out of favor during the heyday of processualism in the 1970s and 1980s it has since begun to return a bit, at least in Chacoan circles, due to some recent developments. While it’s always hard to define concepts like “core” and “periphery” in ways that make them useful in practice, I think it’s pretty reasonable to see the Southwest as outside of Mesoamerica, but significantly influenced by it in many ways.
Mesoamerica doesn’t go on forever, of course, so it has a southern periphery as well. Around the border of Guatemala and Honduras it starts to shade into the very different Central American cultural area, which I think can usefully be seen as in an analogous position to the Southwest. One way it differs, however, is that while the Southwest forms a frontier between the large-scale agricultural societies of Mexico and the hunter-gatherers further north, Central America is really more of a lull between Mesoamerica to the north and the equally sophisticated (but very different) societies of the Andes to the south. Given this intermediate position, the societies of Central America were subject to a complicated and fascinating mix of influences from both directions.
Via Derek Fincham, Maggie Koerth-Baker has two posts at BoingBoing on the archaeology of Costa Rica that make for fascinating reading in this context. The parallels to the Southwest, in both the past (Mesoamerican influence but no state-level societies!) and the present (massive looting!) are remarkable. The website she links to has a lot more information on this little-known but important area. I think its “Conclusions” page is particularly interesting reading from a Southwestern perspective:
Why did the cultural evolutionary process in Costa Rica (and the Intermediate Area in general), similar in its early stages to that observed in Mesoamerica and Peru, sputter and stall? Why did no “urban” centers with large pyramid complexes appear? Robert Carneiro believes that historical evidence shows that no autonomous socio-political unit, large or small, will voluntarily relinquish sovereignty in the name of cooperation or the “greater social good.” Only through forceful domination (war) are states and empires forged. Betty J. Meggers postulates that endemic warfare in an “open” environment like Amazonia, overtly waged for reasons like revenge, supernatural mandates, and the taking of exogamous marriage partners, is, in reality, a regulatory device for human population in an area with a precarious ecological balance. Warfare in Costa Rica may have functioned in this fashion, and may have been even more intense, given greater population densities. Why did this conflict not result in the amalgamation of larger, more complex socio-political structures, as it apparently did in parts of Mesoamerica and Peru? The answer is that oppressed populations could successfully flee the threatened domination, emigrating to other, similar localities instead of being incorporated by force into the larger or more powerful conquering group. William Sanders and Barbara Price, in their essay on the development of “civilization” in Mesoamerica, note that it is not the lack of productive potential in tropical-forest areas like Amazonia that prevented the development of a complex society, but, rather, the presence of huge amounts of at least nominally agricultural land acting as an incentive to successful emigration.
While I’m generally skeptical of attempts to make cross-cultural generalizations on issues like this, I think the relevance of these arguments to several ongoing debates in Southwestern archaeology is clear.