The Xiahe mandible ([ɕjâxɤ̌], sh'ya-khuh) is a hominin fossil jaw (mandible) discovered in Baishiya Karst Cave, located on the northeastern edge of the Tibetan Plateau in Xiahe County, Gansu, China. By the use of palaeoproteomic analysis, it is the first confirmed discovery of a Denisovan fossil outside of Denisova Cave, and the most complete confirmed Denisovan fossil. This fossil discovery shows that archaic hominins were present in a high-altitude, low-oxygen environment around 160,000 years ago. Discover, Science News and Nova all named the discovery of the mandible in their lists of Top Science Stories of 2019.