The Himalayan syntaxes, characterized by extreme rates of rock exhumation co-located with major trans-orogenic rivers, figure prominently in
the debate on tectonic versus erosional forcing of exhumation. Both the mechanism and timing of rapid exhumation of the Namche Barwa
massif in the eastern syntaxis remain controversial. It has been argued that coupling between crustal rock advection and surface erosion
initiated in the late Miocene (8-10 Ma). Recent studies, in contrast, suggest a Quaternary onset of rapid exhumation linked to a purely tectonic
mechanism. We report new multisystem detrital thermochronology data from the most proximal Neogene clastic sediments downstream of
Namche Barwa and use a thermo-kinematic model constrained by new and published data to explore its exhumation history. Modeling results
show that exhumation accelerated to ~4 km/m.y. at ~8 Ma and to ~9 km/m.y. after ~2 Ma. This three-stage history reconciles apparently
contradictory evidence for early and late onset of rapid exhumation, and suggests efficient coupling between tectonics and erosion since the
late Miocene. Quaternary acceleration of exhumation is consistent with river-profile evolution, and may be linked to a Quaternary river-capture
event.