A druid was a member of the priestly class in Britain, Ireland, and Gaul (France), and possibly other parts of Celtic Europe and Galatia during the Iron Age and possibly earlier. Very little is known about the ancient druids. They left no written accounts about themselves and the only evidence is a few descriptions left by Greek, Roman and various scattered authors and artists, also stories created by later medieval Irish writers. While archaeological evidence has been uncovered pertaining to the religious practices of the Iron Age people, "not one single artefact or image has been unearthed that can undoubtedly be connected with the ancient Druids." Various recurring themes emerge in a number of the Greco-Roman accounts of the druids, including that they performed human sacrifice, believed in a form of reincarnation, and that they held a high position in Gaulish society. Next to nothing is known about their cultic practice, except for the ritual of oak and mistletoe as described by Pliny the Elder.