During the Late Middle Paleolithic (-130 / -40 ka) in northern and western Europe, a massivedevelopment in bifacial tools productions has been identified at the end of MIS 5 (-90 / -80 ka) andMIS 3 (-60 / -40 ka). These bifacial tools are characterized by substantial morphological variations,suggesting the existence of regional cultural entities within Neanderthal societies. Thus far, severalsuch entities have been identified based on that variability. This is notably the case of a technocomplexidentified in southwestern part of France: the Mousterian of Acheulean Tradition (MTA). Based on thedistribution of handaxe morphologies, the geographical extent of this entity was initially thought torange from the Loire River to the western Pyrenean Mountains. However, recent research hasquestioned the homogeneity of Late Middle Paleolithic assemblages found in the northern and thesouthern parts of Aquitaine region.In 2018, a collective project supported by the Hubert Curien-Maïmonide program has broughttogether researchers from France, Spain, Portugal and Israel. Our research project applied aninnovative methodological approach for analyzing 3D digital models of handaxes using a combinationof 3D geometric morphometrics with traditional technological observations.Within this framework, 280 handaxes from 13 archaeological sites distributed in twochronological phases (MIS 5 and MIS 3) of the Late Middle Paleolithic and two regional settings(Northern and Southern Aquitaine). Sites were selected according to the reliability of theirchronostratigraphic context and geographical distribution across Aquitaine region.Our results provide new information concerning the variability in handaxes assemblages, bothfrom a diachronic and synchronic point of view, and their possible causes (environmental, functional,cultural). A clear shape-based distinction is identifiable between MIS 5 and MIS 3 handaxes suggestinga strong shift in tradition through time. From a geographic perspective, during MIS 5 handaxes do notshow clear regional differences, while during MIS 3 assemblages originating from north and southAquitaine exhibit strong morphological differences between them supporting interpretation ofregionally separated cultural entities.At this geographic scale, this work has the potential to provide quantitative data which can beused to evaluate hypotheses about population dispersals and their chronology in Western Europe aswell as the mechanisms of interregional interactions between Neanderthal societies during these phases.