The main source for this story is the "Anglo-Saxon Chronicle", a series of annals written in the vernacular Old English. The "Anglo Saxon Chronicle" was commissioned in the reign of Alfred the Great some 400 years after the landing at Cymenshore. One of the purposes of the chronicle was to provide genealogies of the West Saxon kings. Although a lot of the "facts" provided by the chronicle can be verified, the foundation story of Sussex involving Ælle and his three sons can not. It is known that Anglo-Saxons did settle in eastern Sussex during the fifth century, but not in the west where Cymensora was probably situated.