As was often assumed to be the case for mountainous and other mid to high altitude areas, for many years the Pyrenees were considered to be an inhospitable milieu for human Palaeolithic populations. As such, altitude has often been considered among the determinant factors for influencing human settlement, shifting regional archaeologists’ focus away from mid to high altitude areas. However, growing evidence, via the discovery of new karstic and open-air sites in these contexts, has progressively begun to dismantle this assumption. These new indicators underline that mountainous or mid to high altitude environments were inhabited and/or traversed by human populations during different moments throughout the Palaeolithic. This becomes especially relevant when contrasted with the so-called Txingudi corridor, a coastal corridor that may have facilitated passage between both sides of the western Pyrenees. This presentation aims to highlight the evidence that points 1) to settlements in mountainous or mid to high altitude environments, and 2) to the traversal of mountain passes in the western Pyrenees. In the former case, sites contain evidence for a degree of functional specialization (such as the acquisition of lithic resources or hunting), and in the latter, just served as places of passage along the aforementioned mountain routes. Lithics are the most relevant evidence for exploring these questions, especially in regards to lithic raw material procurement patterns, as the presence of northern or southern-Pyrenean resources in sites located in the foothills on either side suggests multiple routes connecting both. Moreover, petrographic analyses indicate variable movements in both directions (north-south and vice versa), and even hiatuses in said movements, across different phases of occupation. The exploration of these patterns across several key Middle and Upper Palaeolithic sites will provide an interesting laboratory for examining questions pertaining to mobility and broader scale population dynamics in the region.