 There is evidence both supporting the theory that much of the present text was authored in the mid-Warring States, and that it was modified after this date.The most systematic study of the "Wuzi's" date of composition and authorship, based on historical references and the book's content, concludes that the core of the work was likely authored by Wu Qi himself, but was likely subject to serious losses of content, revisions, and accretions after his lifetime.This theory assumes that Wu Qi's disciples initially continued amending the text, but cannot account for some content that seems to have been inserted as late as the Han dynasty (possibly in an effort to "update" the work).