The Bar Kokhba hiding complexes are underground hideout systems built by Jewish rebels and their communities in Judaea and used during the Bar Kokhba revolt against the Roman Empire. The hiding complexes are believed to have played a significant role during the revolt, particularly in Judea proper. Functioning as hiding places during times of emergency, these systems facilitated defense strategies and guerrilla warfare tactics. Researchers distinguish among the concealment complexes between those constructed in conjunction with the revolts, which include hiding complexes and cliff shelters, and a different category, the natural refuge caves used as ad hoc hiding places toward the end of the wars.