This research presents the first multitechnique provenance study of the Siwalik Group in the Himalayan foreland basin in India, using the Jawalamukhi section, magnetostratigraphically dated at 13–5 Ma. Combined with provenance data from a Dharamsala Formation sedimentary section (21–13 Ma) located close by, it forms the longest temporally continuous record of Himalayan erosion in the Indian foreland basin. Sandstone petrography and heavy mineral analysis, conglomerate clast composition, Ar‐Ar dating of detrital white micas, and Sm‐Nd analyses on siltstones, conglomerate matrix and conglomerate clasts was undertaken to determine (1) shifts in source region through time and (2) changes in detrital lag times related to exhumation rates in the hinterland, together interpreted in the light of thrusting events. We interpret the data to show a slow down in exhumation rate of the Higher Himalaya by 16–17 Ma, after which time the locus of thrusting propagated south of the Main Central Thrust, and erosion of the low grade Haimanta Formation to the south became significant. The nonmetamorphosed Inner Lesser Himalaya breached its Haimanta cover by 9 Ma with the metamorphosed Inner Lesser Himalaya (Lesser Himalayan Crystalline Series) exhuming to surface by 6 Ma. This event caused sufficient disruption to established drainage patterns that all Higher Himalayan material was diverted from this location at this time.

Single detrital monazite grains from the Dharamsala and Lower Siwalik Formations (early to mid-Miocene continental foreland basin sediments in NW India) have been dated by two techniques; isotope dilution thermal ionization multicollector mass spectrometry (ID-TIMS) and laser ablation plasma ionization multicollector mass spectrometry (LA-PIMMS). The results give U–Th–Pb isotopic ages of c.  400–1300 Ma and 28–37 Ma and suggest that the source of detritus shed from the uplifting Himalayan mountains and captured in the foreland basin included (1) the protolith to the High Himalayan Crystalline Series (HHCS), i.e. rocks unaffected by the Himalayan metamorphism, (2) Cambro-Ordovician granites and (3) HHCS affected by the M 1 phase of Barrovian metamorphism (Eo-Himalayan) related to the Indo-Asian collision. Deposition of the Dharamsala Formation was coeval with M 2 sillimanite grade Himalayan metamorphism and crustal melting. The youngest monazite ( c.  28–37 Ma) ages imply that Indian plate rocks, having experienced the earliest Himalayan metamorphic event which occurred within 10–20 Ma of collision were exhumed, eroded and deposited within c.  10–20 Ma of metamorphism. This indicates a minimum cooling rate of between 60 and 40°C Ma −1 for the period 30–20 Ma. After 20 Ma our study suggests no change in source area and that this same sequence, comprising both metamorphosed and unmetamorphosed rocks, was supplying detritus and being progressively incised by erosion for at least a further 8 million years.