A structural description of the intra-montane basins establishes the deformation field of the southwestern Tian Shan that faces the Pamir and the Afghan-Tajik Basin and thus the Indian mantle indenter beneath the Pamir and the deformation it imposes—northward indentation and westward crustal collapse. Six major Cenozoic faults traceable over >100 km separate rigid basement blocks; tight synclines occupy their footwalls. These ~E-striking faults reactivate Paleozoic ones, indicate ~N-S shortening with a dextral strike-slip component, connect with ~WNW-striking ones with a strong dextral component, and ~ENE-striking ones confined to the western southwestern Tian Shan. The deformation field resembles that in the Afghan-Tajik Basin fold-thrust belt, and mimics in shape the geometry of the intermediate-depth earthquake zone beneath the Pamir. We infer that the southwestern Tian Shan is involved in the northward motion and westward collapse. The basement-rooted Cenozoic faults require a detachment underlying the southwestern Tian Shan, which should root in the delamination zone beneath the Pamir; a depth of the detachment at the brittle-ductile transition is consistent with the regular spacing of the intra-montane basins. A crustal-scale cross section connects the southwestern Tian Shan, the Afghan-Tajik Basin fold-thrust belt, and the delamination zone, and highlights the evaporite-detachment below the Afghan-Tajik Basin, the mid-crustal detachment below the southwestern Tian Shan, and the rooting of faults of the Afghan-Tajik Basin fold-thrust in the deeper detachment; this may run along the Moho.