It is problematic to date ‘Common Celtic law’, and the best we can arrive at are rough estimates. It is quite apparent, by parallels existing between Celtic and other Indo-European laws that at least some of the legal principles that make up Common Celtic law must be very ancient, perhaps going back to the Early Bronze Age or even the Neolithic period. Others may have only developed much later, perhaps even only as a result of contacts with Mediterranean cultures (mainly Greeks and Romans) during the late Iron Age and Antiquity.