Peking Man (Homo erectus pekinensis, originally "Sinanthropus pekinensis") is a subspecies of H. erectus which inhabited what is now northern China during the Middle Pleistocene. Its fossils have been found in a cave some 50 km (31 mi) southwest of Beijing (referred to in the West as Peking upon its first discovery), known as the Zhoukoudian Peking Man Site. The first fossil, a tooth, was discovered in 1921, and Zhoukoudian has since become the most productive H. erectus site in the world. Peking Man was instrumental in the foundation of Chinese anthropology, and fostered an important dialogue between Western and Eastern science. Peking Man became the centre of anthropological discussion, and was classified as a direct human ancestor, propping up the Out of Asia theory that humans evolved in Asia.
Peking Man also played a vital role in the restructuring of Chinese identity following the Chinese Communist Revolution, and it was used to introduce the general populace to Marxism and science. Early models of Peking Man society were compared to communist or nationalist ideals, leading to discussions on primitive communism and polygenism (that Peking Man was the direct ancestor of Chinese people). This produced a strong schism between Western and Eastern interpretations of the origin of modern humans, especially as the West adopted the Out of Africa theory in the late 20th century, which described Peking Man as an offshoot in human evolution. Though Out of Africa is now the consensus, Peking Man interbreeding with human ancestors is still discussed.