Liu Xin, courtesy name Zijun, was a Chinese astronomer, classicist, librarian, mathematician, and politician during the Western Han and Xin dynasties. He later changed his name to Liu Xiu (劉秀) due to the naming taboo of Emperor Ai of Han. He was the son of Imperial librarian Liu Xiang and an associate of other eminent thinkers such as the philosopher Huan Tan. Liu was a prominent supporter of the Old Text classics.

The Book of Han 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. The work was composed by Ban Gu, 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, 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 of the Former Han to distinguish it from the Book of the Later Han which covers the Eastern Han period from 25 to 220 CE, and was composed in the fifth century by Fan Ye.