Guyaju Caves (古崖居) are the ruins of a cave complex that may have served as dwellings for a fortified community situated in a valley near present-day Dongmenying, Yanqing District, Beijing, China. The origins of the community are mysterious due to uncertainty about the founding people and later disappearance of the community. The settlement may have been established by a tribe of people belonging to the Kumo Xi during the Liao Dynasty. Other theories are the complex was built by outlaws on the run or served as a military garrison during the Tang Dynasty. However, there are no clear answers as to the history of the caves with the historical literature stressing "its origins are a continuing archeological cipher."