The document provides background information on the Arthurian legend. It discusses how the Celts arrived in Britain and their religious practices under the Druids. It then describes how Britain was later conquered by the Romans who brought Christianity. Several enemies threatened the Britons, including the Picts, Gauls, Saxons, Goths, and Visigoths. The first chronicler of Arthur was Geoffrey of Monmouth in the 12th century, though his work was largely fictional. It was later argued that Arthur was likely the historical figure Riothamus, a high king of the Britons. The document concludes with an overview of events prior to Arthur's birth, including descendants of a Trojan prince who fled to Britain and