The first mention to Laozi is in the "Records of the Grand Historian" by Sima Qian. In one account, he was an official who lived around the time of Confucius. His name was "Er Li" or "Dan Li", and he wrote some a book with two parts before leaving west. In another, he has the name "Lao Laizi", and the book has 15 parts. In a third, he appears as a royal astrologer named "Lao Dan" living at the time of Duke Xian during the Qin Dynasty. The oldest Daodejing writing comes from around 375 BCE.