Gu Jiegang
In the late 19th and early 20th centuries, following Kang Youwei, the book was often seen as a forgery by Liu Xin. Currently, a few holdouts continue to insist on a Western Zhou date while the majority follow Qian Mu and Gu Jiegang in assigning the work to about the 3rd century BC. Yu Yingshi argues for a date in the late Warring States period based on a comparison of titles in the text with extant bronze inscriptions and calendrical knowledge implicit in the work In this view, the word "Zhou" in the title refers not to the Western Zhou but to the royal State of Zhou of the Warring States; the small area still directly under the king's control.