Since the Formative Period (700 B.C. - A.D. 700), Quillagua (Lower Loa river basin) has demonstrated social interaction with populations from the adjacent Tarapaca and Atacama regions, an interaction that is particularly conspicuous during the Late Intermediate Period (A.D. 900 - 1400). The primary indicators of this interaction are textiles from funerary contexts, particularly tunics that show differences in shape and are associated with different regions. In this context, we present an analysis of a group of anthropomorphic paintings from the Middle and Upper Loa River region that depict individuals in tunics. Our analyses of rock art figures allow us to suggest that the co-traditional or "soft-border" zone models presented for Quillagua can be extended to the rest of the Loa river basin.