The Yi Zhou Shu (simplified Chinese: 逸周书; traditional Chinese: 逸周書; pinyin: Yì Zhōu Shū; Wade–Giles: I Chou shu; literally: "Lost Book of Zhou") is a compendium of Chinese historical documents about the Western Zhou period (1046–771 BCE). Its textual history began with a (4th century BCE) text/compendium known as the Zhou Shu ("Book of Zhou"), which was possibly not differentiated from the corpus of the same name in the extant Book of Documents. Western Han dynasty (206-9 BCE) editors listed 70 chapters of YZS, of which 59 are extant as texts, and the rest only as chapter titles. Such condition is described for the first time by Wang Shihan 王士漢 in 1669. Circulation ways of the individual chapters before that point (merging of different texts or single text's editions, substitution, addition, conflation with commentaries etc.) are subject to scholarly debates (see below).
Traditional Chinese historiography classified the Yi Zhou Shu as a zashi 雜史 "unofficial history" and excluded it from the canonical dynastic Twenty-Four Histories.
This early Chinese historical text has four titles: Zhou zhi, Zhou shu "Documents/Book of Zhou", Yi Zhoushu "Lost/Leftover Documents/Book of Zhou", and Jizhong Zhou shu "Ji Tomb Documents/Book of Zhou".
Zhou zhi 周志 appears once throughout the transmitted texts: in the Zuo zhuan (Duke Wen, 2 - 625 BC), along the quote presently found in YZS. The reference is valuable since it differentiates YZS from the corpus of other documents shu and possibly refers to its educational function.
Zhoushu (or Zhou shu) – combining Zhou "Zhou dynasty" and shu "writing; document; book; letter" – is the earliest record of the present title. Depending upon the semantic interpretation of shu, Zhoushu can be translated "Book(s) of Zhou" (cf. Hanshu 漢書 Book of Han) or "Documents of Zhou" (cf. Shujing 書經 Book of Documents). In Modern Standard Chinese usage, Zhoushu is the title of the Book of Zhou history about the later Northern Zhou dynasty (557-581).