Sima Tan was an early historian who worked under the Western Han. He was the father of Sima Qian, who upon the death of Sima Tan, took up his father's work and completed the 130 volume ''Records of the Grand Historian''.
An essay by him has survived within the ''Records of the Grand Historian''. It is an assessment of the six major philosophical traditions of his day: Confucianism, Daoism, Legalism, Mohism, Terminalism and . Sima Tan himself was a follower of Huang Lao, an early Han form of Daoism.
Sima Qian also gives a few other details about his father's life. He studied astronomy with Tang Du, the ''I Ching'' under Yang He and Daoism under Master Huang. He held the position of Grand Historian between 140-110 BC.