The pre-Neolithic history of the Tibetan Plateau is virtually unknown. Test excavations of Late Paleolithic sites, described here, provide preliminary evidence that the initial occupation of the plateau's extreme environments was by small groups of foragers probably traveling from lower elevation plateau margins. These foragers occupied very short-term camps focused on the procurement and extensive processing of small-to-medium mammals. Five separate occupations date to 13–15,000Cal yr BP, but limited survey data suggest mid-elevation locations may have been temporarily occupied as early as 25,000years ago. Full-time, year-round occupation of the plateau probably did not take place until the early Neolithic advent of domesticated animals.