 It relates the purported history of Britain, from its first settlement by Brutus of Troy, a descendant of Trojan hero Aeneas, to the death of Cadwaladr in the 7th century, covering Julius Caesar's invasions of Britain, Kings Leir and Cymbeline, and one of the earliest developed narratives of King Arthur.Geoffrey claims in his dedication that the book is a translation of an "ancient book in the British language that told in orderly fashion the deeds of all the kings of Britain", given to him by Walter, Archdeacon of Oxford, but modern historians have dismissed this claim.It is likely, however, that the Archdeacon did furnish Geoffrey with some materials in the Welsh language which helped inspire his work, as Geoffrey's position and acquaintance with him would not have permitted him to fabricate such a claim outright.