The Book of Han (Hàn Shū,《漢書》) is a history of China finished in 111 CE, covering the Western, or Former Han dynasty from the first emperor in 206 BCE to the fall of Wang Mang in 23 CE.^[1] The work was composed by Ban Gu (32–92 CE), an Eastern Han court official, with the help of his sister Ban Zhao, continuing the work of their father, Ban Biao. They modelled their work on the Records of the Grand Historian,^[2] a cross-dynastic general history, but theirs was the first in this annals-biography form to cover a single dynasty. It is the best source, sometimes the only one, for many topics such as literature in this period. The Book of Han is also called the History (or Book) of the Former Han (Qián Hàn Shū,《前漢書》) to distinguish it from the Book of the Later Han (Hòu Hàn shū 《後漢書》) which covers the Eastern Han period from 25 to 220 CE, and was composed in the fifth century by Fan Ye (398–445 CE).^[3]

This history developed from a continuation of Sima Qian's Records of the Grand Historian, initiated by Ban Gu's father, Ban Biao, at the beginning of the Later Han dynasty. This work is usually referred to as Later Traditions (後傳), which indicates that the elder Ban's work was meant to be a continuation. Other scholars of the time, including Liu Xin and Yang Xiong also worked on continuations of Sima's history. After Ban Biao's death, his eldest son Ban Gu was dissatisfied with what his father had completed, and he began a new history that started with the beginning of the Han dynasty. This distinguished it from Sima Qian's history, which had begun with China's earliest legendary rulers. In this way, Ban Gu initiated the Jizhuanti (紀傳體，纪传体) format for dynastic histories that was to remain the model for the official histories until modern times.

For the periods where they overlapped, Ban Gu adopted nearly verbatim much of Sima Qian's material, though in some cases he also expanded it. He also incorporated at least some of what his father had written, though it is difficult to know how much. The completed work ran to a total of 100 fascicles 卷, and included essays on law, science, geography, and literature. Ban Gu's younger sister Ban Zhao finished writing the book in 111, 19 years after Ban Gu had died in prison. An outstanding scholar in her own right, she is thought to have written volumes 13–20 (eight chronological tables) and 26 (treatise on astronomy), the latter with the help of Ma Xu. As with the Records of the Grand Historian, Zhang Qian, a notable Chinese general who travelled to the west, was a key source for the cultural and socio-economic data on the Western Regions contained in the 96th fascicle. The "Annals" section and the three chapters covering the reign of Wang Mang were translated into English by Homer H. Dubs.^[4] Other chapters have been rendered into English by A. F. P. Hulsewé, Clyde B. Sargent, Nancy Lee Swann, and Burton Watson.

The text includes a description of the Triple Concordance Calendar System 三統曆 developed by Liu Xin in fascicle 21. This is translated to English by Cullen.^[5]

Ban Gu's history set the standard for the writings of later Chinese dynasties, and today it is a reference used to study the Han period. It is regarded as one of the "Four Histories" 四史 of the Twenty-Four Histories canon, together with the Records of the Grand Historian, Records of the Three Kingdoms and History of the Later Han.