What is the X in X-mas?
(from Old English Su Seaxe, South Saxons), one of the kingdoms of Anglo-Saxon England. It ultimately coincided in area with the modern counties of East Sussex and West Sussex, although Hastings in East Sussex appears to have been sometimes separate. According to the tradition preserved in the Anglo-Saxon Chronicle, a certain Aelle landed in AD 477 at a place now covered by the sea, south of Selsey Bill, and defeated the Britons. Archaeological evidence suggests that there was Germanic settlement in the area beginning in the 5th century. The Venerable Bede, writing in the 8th century, says that Aelle held supremacy over all the peoples south of the Humber, the only king of Sussex to hold that eminence. In the 680s St. Wilfrid, expelled from Northumbria, spent several years converting the South Saxons to Christianity. At that time their king was Aethelwalh, but after his death Sussex was divided among several kings. There were still kings early in the reign (757-796) of Offa of Mercia, but later they are named as ealdormen. In the 9th century Sussex fell to the kings of Wessex.