Examining the spatio─temporal boundaries of the Guaraní expansion into the La Plata basin
Channel: Recording Archaeology
Date: 2016-08-24

The direction and timing of the Guaraní expansion into the La Plata basin from an Amazonian origin is a matter of no small debate in the study of South American indigenous cultures. The short timeframe of the Guaraní expansion (2000–500 BP) during the late Holocene, as well as the distances involved, are both used to explain it as the result of the migration of significant numbers of people in a classic “wave of advance”. The process is further broken down into “pulses” punctuated by periods of relative stasis in which colonization through the valleys of major rivers was halted or slowed. These factors, combined with a broad base of empirical data from decades of research, provide the impetus for refining established chronologies of the Guaraní dispersal. We use a published database of georeferenced dates to model its spread at the beginning of the Common Era from a presumed entry point until the time of European contact at its known limits at the La Plata delta and Atlantic coast of Brazil. Using regression models and Monte Carlo methods, we examine the dispersal in order to constrain the probable start dates for entry into different zones. Additionally, we investigate the notion that Guaraní groups enveloped large sectors of terrain contiguously as the result of demographic pressures that were interspersed, as noted, with hiatuses of comparatively little movement. We place our findings in the context of preceding archaeological, ethnographic, and ethnohistorical knowledge on this uniquely South American process of indigenous dispersal. Suggestions for further work to improve the scenarios we present are offered, following the note by Brochado (1984) that in the study of Guaraní archaeology, “computer modelling is probably the only way to achieve refined estimates of population growth” in the La Plata basin.

Phil Riris, Fabio Silva