The Welsh started to refer to themselves as Cymry (fellow countrymen), not by the Saxon term used by English-speakers today, which is generally thought to mean either foreigners or the Romans.
Wales, like England in the Dark Ages, was a land of multiple kingship’s. The rugged terrain, with impenetrable mountain massifs and inhospitable upland ranges, broken by river valleys.
The boundary with England was not marked by natural defenses, and productive lowland areas as well as profitable upland pastures. Not until King Offa of Mercia built his dyke in the second half of the 8th century was there a definable frontier, and that was designed mainly to deter Welsh attacks and control trade across the new border.
It was much the longest as well as the most striking man-made boundary in the whole of western medieval Europe, and clearly came to play an important role in shaping the perception of the extent and identity of Wales.
Towards the end of the 6th century the Angles and Saxons in eastern Britain began to entertain designs on the western lands. The inability of the independent western peoples to unify against this threat left the most powerful kingdom, Gwynedd, unable to hold the invaders.
Though still geographically in a state of change, Wales could now be said to exist. At this point, the racial mix in Wales was probably little different from that to the east, where Saxon numbers were small, but Wales was held together by the people’s resistance to the Saxons.