China has one of the world's oldest and continuous civilizations, consisting of states and cultures dating back more than six millennia. It has the world's longest continuously used written language system, and is viewed as the source of many major inventions. Historically, China's cultural sphere has extended across East Asia as a whole, with Chinese religion, customs, and writing systems being adopted to varying degrees by neighbors such as Japan, Korea and Vietnam. The first evidence of human presence in the region was found at the Zhoukoudian cave and is one of the first known specimens of Homo erectus, now commonly known as the Peking Man, estimated to have lived approximately from 300,000 to 550,000 years ago.