Many petroglyphs were left by the Ming Dynasty crown prince Chu Yi-hai around the Gugang Lake area. Of the petroglyph "Hanyingyungen" ("Han's Shadow, Cloud’s Root"), only the three characters "Han's Shadow, Cloud’s... " remain today and has since been declared a class 3 national historical monument. In 1970 the Department of Social Education inscribed a full copy of the inscription on to another boulder nearby.