ABSTRACT This chapter focuses on the role of basement fabrics and inverted extensional faults that strongly affect the frontal zones of the fold-and-thrust faults of sub-Andean basins in Peru and Bolivia. This review examines the relationships of hinterland deformation in the basement with the Present Day topography from the Andean plateau to the sub-Andean foreland basin. Preexisting, steep basement–involved extensional faults that were inverted in the last phase of Andean deformation (~10 Ma to the Present Day) produced basement-cored uplifts that transferred thick-skinned shortening eastward onto the thin-skinned thrust fault and fold systems detached above the basement. Regional cross sections are reviewed and revised in the light of analysis of seismic data as well as mechanically feasible models of the hinterland to foreland transfer of displacement. Steep inverted faults with dominantly high vertical uplift in the hinterland exhume the older stratal packages together with crystalline basement, and these units provide the source for the largely Neogene to Holocene syn-tectonic foreland basins in front of the advancing thrust wedge of the sub-Andean system in Peru and Bolivia.