The document provides background information on the Arthurian legend. It discusses how the Celts arrived in Britain and their religious practices under Druids. It then describes how Britain was later conquered by the Romans who brought Christianity. It notes the enemies of the Britons, including the Picts, Gauls, Saxons, Goths, and Visigoths. It also discusses the first chronicler of Arthur, Geoffrey of Monmouth, and evidence that Arthur may have been the historical figure Riothamus.