The origins and spread of the Mysteries have been intensely debated among scholars and there are radically differing views on these issues. According to Clauss mysteries of Mithras were not practiced until the 1st century CE. According to Ulansey, the earliest evidence for the Mithraic mysteries places their appearance in the middle of the 1st Century BCE: The historian Plutarch says that in 67 BCE the pirates of Cilicia (a province on the southeastern coast of Asia Minor) were practicing "secret rites" of Mithras. However, according to Daniels, whether any of this relates to the origins of the mysteries is unclear. The unique underground temples or mithraea appear suddenly in the archaeology in the last quarter of the 1st century CE.