Early settlements in the Uruguay river basin: a new reading based on recent data from Uruguay and Brazil

• We provide a unified approach to the first settlements in the Uruguay River basin. • Lithic productions show a shared background, but regionalization along the valley. • Chronological and cultural data point to a south-to-north settlement dynamic. • The Uruguay basin and Atlantic slope show two different settlement processes. We present an updated synthesis of archaeological evidence relating to the earliest settlements in the Uruguay River basin, between 13,300 and 9300 cal BP. We propose a unified approach to these data, focusing preferentially on current research, which is concentrated in two regions of the Uruguay River, for which there is a good stratigraphic and chronological resolution and a good description of the archaeological record. Our approach was developed on two levels: a review of available radiocarbon dates, and a study of lithic productions using a single analytical grid. The results allow us to: 1) highlight a technological link between human occupations in the Uruguay Basin while revealing regional differences; 2) highlight changes over time, with sequences specific to both regions; 3) perceive a settlement dynamic from South to North, up the river. Putting these data into perspective in southern Brazil and Uruguay, we can see that the North-South variation between the two countries may have been overestimated, due to differences in research traditions. In fact, there is more of an East-West distinction in archaeological contexts, linked to two distinct settlement dynamics: the Uruguay River basin on the one hand, and the Atlantic slope on the other.