No record has been preserved of the immediate successors of St. Kentigern, and shortly after his death and the death of his protector, Rydderch, the whole of the Cumbrian and adjoining Anglic districts, the latter stretching northward to the Forth, were thrown into confusion by the revolution which restored paganism for a time under the pagan Mercian King, Penda, and the apostate Welsh King, Ceadwalla. In 633 King Oswald established the Columban Church in Northumbria, and as the kingdom of the Britons, a few years later, fell under the dominion of the Angles, it is probable that during the period of their rule there would be no independent church there. Consequent on the defeat inflicted by the Picts on the Anglian army at Dunnichen, in 685, the Britons inhabiting those districts north of the Solway, embracing the area now represented by the counties of Dumbarton, Renfrew, Lanark, Ayr and Dumfries, with the stronghold of Alclyde as the chief citadel of their territory, recovered their liberty, and two years later they conformed to the practice of Rome in observance of the proper time of keeping Easter, then a matter of the greatest importance from an ecclesiastical point of view. About that time one, Sedulius, who was present at a council held at Rome in the year 721, has been associated with the Britons of Strathclyde as their bishop. [Skene's Celtic Scotland, ii. pp. 199, 219, 260, 265.]

In his Life of Kentigern, Joceline tells us that he "joined to himself a great many disciples whom he trained in the sacred literature of the Divine Law, and educated to sanctity of life by his word and example. They all, with a godly jealousy, imitated his life and doctrines, accustomed to fastings and sacred vigils at certain seasons, intent on psalms and prayers and meditation on the Divine Word, content with sparing diet and dress, occupied every day and hour in manual labour. For, after the fashion of the primitive church under the Apostles and their successors, possessing nothing of their own, and living soberly, righteously, godly and continently, they dwelt as did Kentigern himself, in single cottages, from the time when they had become mature in age and doctrine. Therefore these solitary clerics were called in common speech Calledei." On this passage Dr. W. F. Skene remarks that in assigning the Keledei of Glasgow to the time of Kentigern Joceline is guilty of as great an anachronism as when he assigned to him Servanus as a teacher. [Antea, p. 13.] Joceline wrote when there existed bodies of Keledei in Scotland, and he is no doubt repeating a genuine tradition as to the original characteristics of the Culdean clergy before they became canons. What he describes is simply a community of anchorites or hermits. Servanus was contemporary with Sedulius, bishop of the Britons, and it is to this period that these Keledei of Glasgow properly belong. This connection with the real Servanus, Dr. Skene thinks, may have led to the history of this period having been drawn back, and both Keledei and Servanus associated with the great apostle of Glasgow in popular tradition. [St. Kentigern, p. 66; Celtic Scotland, ii. p. 260.]

After this we have no connected historical account of the Britons for a long time to come, but it is known that in 756 they surrendered to Eadbert, King of Northumbria, and Angus, King of the Picts, and that these invaders took Alclyde, which was burnt in 780. In the next century the territorial name Britons of Strathclyde or Strathclyde Welsh was for the first time applied to the inhabitants who had hitherto borne the general name of Britons. Thus the Irish Annals narrate that Artgha, King of the Britons of Strathclyde, was killed in 872, and the Saxon Chronicle tells that in 875 the Danes subdued the whole of Northumbria and ravaged the Picts and the Strathclyde Welsh. It is in a narrative of this event, written by the chronicler Ethelwerd, between 975 and 1011, that the name Cumbrians is for the first time applied to the inhabitants of Strathclyde. [Celtic Scotland, i. p. 295; St. Kentigern, p. 332; Scottish Annals, p. 62.]

It is understood that in the ninth century the people dwelling in the regions north of the Solway, including Strathclyde, and the Picts of Galloway were independent of the Angles and of each other, and that the Angles still maintained a hold upon the district south of the Solway. In the following century, however, the name of Strathclyde Welsh passed into that of Cumbri, and in the Saxon Chronicle, under the year 945, the important announcement is made that Edmund, King of Wessex, "harried all Cumbraland and gave it to Malcolm, King of the Scots." Whether the ceded district consisted of the area on the south of the Solway or that on the north of the Solway, or both together, is doubtful, and in any case the transaction was probably little more than nominal. For a long time after 945 Strathclyde remained in active hostility to the King of Scots, but in the year 1018 Owen, its last independent King, died, and the second Malcolm was then able to appoint his own grandson as Owen's successor. [Celtic Scotland, i. pp. 362, 393-4.]

No fewer than six Kings are named as reigning in Scotland between the time of Malcolm I. (942-54) and that of Malcolm II. (1005-34) in which latter reign Lothian was ceded to the Scots and the several territories were thenceforth designated the kingdom of Scotia. But it was not till the consolidation of feudal Scotland under King David, in 1124, that Cumbria was more than a dependency of the Scottish kingdom, and there had been periods when even that relationship was not maintained. One notable break occurred during the reign of Macbeth (1040-57), who does not appear to have ruled south of the Forth; and, between the death of Malcolm III. and the accession of Edgar, it seemed as if the Forth was again to be the southern boundary. Throughout Edgar's comparatively peaceful reign of nine years some difficulties were experienced in ruling the combined territory, on account of diversity of race and complications of a political nature, and historians are of opinion that it was for this reason that, on Edgar's death, Scotland proper was assigned to Alexander, with the title of King, while David, the younger brother, ruled the southern district as Earl. This latter territory—Cumbria, Teviotdale and part of Lothian—the scene of many old rivalries between aboriginal Britons, Saxon and Norse invaders, and nearer neighbours, the Picts and Scots, comprehended the area now included in the countries of Lanark, Renfrew, Ayr, Dumfries, Peebles, Selkirk and Roxburgh, with adjoining districts not precisely defined. Many places throughout these bounds soon rose into prominence when placed under the able administration of Earl David, who had exceptional advantages for ruling the Border country. On account of his sister being the wife of King Henry, and his own marriage bringing with it substantial interest in England, he was in his younger days in close relationship with the English court. This intimacy with the southern country accelerated the Anglo-Saxon and Norman immigration, which had been going on since the arrival of Queen Margaret, and it was not long till most of the land, other than the portions retained as royal domain or gifted to the church, was in the possession of the new settlers as overlords. It is thought, however, that the native population would continue to occupy their previous holdings as cultivators of the soil, and, if this view be correct, the introduction of the new feudal overlords probably caused little or no disturbance. The protection which a powerful chief could extend to his vassals and tenants would counterbalance other disadvantages and reconcile the old possessors to the change.