This research report traces the history of route books (genglubu) from their chance discovery in 1974. It assesses the credibility of these practical nautical guide books as historical sources employed by official agencies in mainland China to claim permanent Chinese occupation of islands in the South China Sea. The route books of Hainan fishermen have a rather short history, having been laid down in writing only in the early 20th century. As contemporary practical nautical guides, they complement the established order of pre-modern Chinese texts used in official publications to describe the South China Sea as historical Chinese territory.
