Traditional accounts place Laozi in the 6th century BC, as a keeper of archival records at the Zhou court in China and an older contemporary of Confucius. In the Records of the Grand Historian, the Han historian Sima Qian writes that he wrote a book in two parts before departing to the west.
Historians disagree about how much of this is true: some regard the traditional Laozi as largely or wholly legendary, while others think a historical figure is plausible. The book attributed to him, the Tao Te Ching, includes later additions, and some scholars date most of it to the 4th century BC.