vales of the Clwyd and Conway, the promontory of Lleyn, the fastnesses of Snowdon and Cader Idris, and the comparatively fertile plains of the Isle of Môn, not yet known as Anglesey, their "principal seat" being at Aberffraw, a small port near Holyhead, whose history goes back to the days of Cadwalader, the contemporary of Oswy. But the superiority of the house of Cunedda, from whom Cadwalader descended, was often merely honorary, and it had long been challenged by princes of South Wales, the Dextralis pars Britanniae, as the Welsh termed it. In this, the more spacious and less mountainous half of Wales, a fairly strong principality, later to be known as Deheubarth, was emerging out of conquests made by Seisyll of Ceredigion at the expense of Dyfed, Ystrad Tywi and Brycheiniog. The larger part of these districts in the course of the eighth century were tending to unite under one chief, and already in Offa's day men regarded Dinefwr on the Towy, some fifteen miles east of Carmarthen, as a principal seat or capital, the possession of which carried with it the primacy of South Wales.
For judicial and fiscal purposes most of the tribal units were subdivided into "cantrefs" of very varying sizes, but on the average rather larger than the English hundreds, each of which in theory was built up of a hundred "trefs" or hamlets. For ecclesiastical purposes there were yet other divisions. Out of the many monastic churches founded in the sixth century four had come to stand out as the most important and had become centres of episcopal organisation. These were Bangor and Llanelwy, otherwise St Asaph, in Northern Wales, Llandaff in Morgannwg, and Mynyw (in Latin Menevia), otherwise St David's, in Dyfed. The Welsh Church, too, no longer held aloof from Rome as in earlier days. About 768 it had adopted the Roman Easter, led by Elbodug, a monk of Caer Gybi or Holyhead, and a student of Bede's works. To Wales this peaceful revolution meant as much as the decision come to at Whitby had meant for England a hundred years earlier. With the acceptance of the Roman date for Easter, Wales threw itself open to the influence of the Continent, and not only so, but also to greatly increased intercourse of a non-military character with the English kingdoms. At the date of the fight at Rhuddlan, Elbodug was still living. He died about 809, "chief bishop in the land of Gwynedd." Among his disciples was Nennius, famed as the editor of the Historia Brittonum, from which come so many of the folk tales concerning Arthur and the first coming of the Saxons into Britain. Nennius seems to have lived in Deheubarth, probably near the borders of Brycheiniog. He was writing just about the time that Coenwulf ascended the Mercian throne, and his book soon aequired a considerable popularity, not only in Wales, but also in England, Ireland, and Brittany. Nemnius wrote shocking Latin, and complains that incessant wars and pestilence had dulled the senses of the Britons; but his work, puzzle-headed as it is, shews that the monasteries of Wales still
