Sima Qian says Laozi was tired of the moral decay in Chengzhou. The kingdom was declining. He traveled west and lived on the frontier until 80. He was recognized by the guard Yinxi at a western gate. Yinxi asked Laozi to write his wisdom. This became the Daodejing. But the present version of the text includes additions from later periods. In some versions of the tale, Yinxi liked the work so much that he became a student and left with Laozi, never to be seen again. In others, the "Old Master" traveled all the way to India and was the teacher of Siddhartha Gautama, the Buddha. Others say Laozi was the Buddha himself.