The massive Iron Age hillfort at Cissbury was supposedly named for Cissa, one of the sons of the pseudo-mythological figure Ælle, who, accordingly to the Anglo-Saxon chronicle was purportedly the first king of Sussex and bretwalda of Germanic peoples south of the Humber. It has been argued that the town of Chichester (Roman Noviomagus Regnensium) was also named for Cissa and was the seat of his kingship after Ælle died, although there is apparently no evidence for sub- or post-Roman settlement within Chichester between the fifth and seventh centuries. Similarly, although there is evidence for occupation within the Cissbury earthworks from the neolithic until the end of the Roman period, excavations there have not found any evidence for early medieval settlement within the earthworks, nor indeed elsewhere on the surrounding downland.
It is clear from the Anglo-Saxon Chronicle that the Anglo-Saxons, even as late as the ninth century when those documents were compiled, were obsessed with genealogy, perhaps assuming that invoking potent ancestors, they promoted their own legitimacy. This has been argued as a reason for the placement of early medieval burials adjacent to, or within, earlier Bronze Age tumuli; in placing the bodies of their kin in association with earlier monuments, the social group attempted to exercise local territorial control. Local elites may have taken these famous `ancestors’ as real ones. A family of local importance may have fabricated descent from a figure known in stories which became the basis for the earliest entries in the Anglo-Saxon chronicle, just as King Alfred traced his family back both to the pagan god Woden and, ultimately, the biblical Adam. A kin-group would then advertise this legitimacy. In West Sussex there were the Wlencingas, descendants of another son of Ælle, which became Lancing; or dwellers on the coast of Selsey where Ælle’s last son was purported to have landed became known as Cimenshore.
By imbuing the landscape with the names of mythical heroes and other dramatis personae, the people of Sussex may have reinforced a common social identity, possibly in the face of some type of stress. Sussex was conquered by Cædwalla of Wessex in 684 or 685 and no longer had its independence, becoming a satellite to Mercia in the eighth century and later a shire of Wessex during the reigns of Æthelwulf and Alfred. They were mentioned as a distinct group as late as the A.D. 1000s: a wave of Viking raids in the eleventh century was recorded as taking place “in the land of the South Saxons” in the first decade of that century. Perhaps in order to reinforce the sense of social identity, a myth sprang up about South Saxon glory of ages past. The people might have spoken of the legendary warrior Cissa who fought battles in the very lands where they walked, and erected impressive fortifications, such as those that still survive at Cissbury, but are in fact over 1,000 years older than the first Germanic settlers in West Sussex.