Sima Guang (1019-1086) was a renowned historian and high-rank official in Northern Song Dynasty. With the courtesy name of Junshi, he was a native of Xiaxian county in Shanxi province. He was a successful candidate in the highest imperial examinations. During the reign of the Emperor Yingzong, he first worked as local government officials and then higher-rank officials in the central government. He began to compile the eight-volume history book during the reign of Emperor Yingzong. The book was named History as a Mirror, when he served as a senior official at the imperial academy, or Hanlin Academy Chinese. He was an opponent to the new policies proposed by reformist Wang Anshi and had launched several debates against Wang and his colleagues. As the reformists won support from Emperor Shenzong, he retreated to Luoyang, devoting 15 years of energy to compiling the History as a Mirror. During the reign of Emperor Zhezong, he tried to restore the old systems by defeating the reformists under the support of the Dowager Empress Gao. Sima Guang's greatest contribution was the 249-chapter History as a Mirror, recording history from the Warring States period to Northern Zhou Dynasty, aiming to offer historical experiences and lessons to rulers of the country. His poems and literary works were included in the Sima Wengong Collection.