North of the Himalayas is the Tibetan plateau-the largest physiographic feature on Earth related to intercontinental collision.Here, we study the rugged Gangdese Range along the southern drainage divide of the Tibetan plateau using a synthesis of geologic, thermochronologic, and interseismic geodetic observations that reveal that southern Tibet's Gangdese Range is undergoing active surface uplift at present-day rates rivaling the Himalaya.Uplift has likely been sustained since the early Miocene, and we hypothesize that surface uplift of the Gangdese Mountains led to the development of Tibet's internally drained plateau, as well as potentially reversed the course of the paleo Yarlung River, in tandem with exhumation of the Himalayan gneiss domes.We suggest the data are consistent with active thrust duplexing, balanced by upper crustal extension, effectively extending the active décollement between the underthrusting Indian plate and the Eurasian upper plate more than 200 km north of the High Himalayas.