The mac Alpin dynasty ruled in the male line (with one exception), until 1034 and the death of Malcolm II. Yet direct patrilineal succession was not established in that period. Without exception grandsons and cousins (or occasionally, as in 858 and 877, brothers) succeeded rather than sons, although the long reigns of Constantine II (900 -43), Kenneth II (971 -95) and Malcolm (1005 -34) somewhat obscured the usual rotation between different segments of the royal kindred. Also, of the fourteen kings between the death of Kenneth in 858 and 1034, no fewer than five reigned for five years or less and further four survived less than ten. To them should be added the sizeable number of royal sons-in-waiting who died by violence whether at the hands of foreign invaders or, more often, of members of their own kindred (such as Olaf, son of Indulf, killed by his rival from the other segment of the royal family, or Kenneth, son of Malcolm in 977). The average length of reign was twelve years, testimony not only to the violent hazards still attached to kingship but also to the fact that many well have succeeded only when well into middle age. Part of the novelty of the long reign of Malcolm II may have been that it induced confusion within the system of segmentary selection and produced not one but two mature candidates - Duncan and Macbeth. Novel, too, at least in this period, was the fact that Duncan must have been a young man, quite unlike the role later cast for him in Shakespeare's play Macbeth. This was the dynasty which, it may fairly be claimed, oversaw the vital consolidation of the kingdom of the Scots but it - a family which had failed twice in the male line in the course of a century and a half - was not a particularly stable vehicle in control of the process.

The second half of the tenth century, lying between the end of the long reign of Constantine II in 943 and the accession of Malcolm II in 1005, saw recurrent disputes over the succession and reversionary interest which often ended in attempted coups. The only reign of any length within the period was that of Kenneth II but it is likely to have been just as marked by unrest throughout much of its length as was it ends, which came when Kenneth was killed, according to the Annals of Ulster, by the 'treachery' of his own subjects. His death was only one of many manifestations of a long-standing feud between the two main segments of the mac Alpin dynasty which had begun before his reign of four years, Dubh ('the black') son of Malcolm I (962-6) was challenged twice by his rival and eventual successor Culen (966 -71), first unsuccessfully somewhere in Atholl and then at Forres ' by the treacherous nation of Moray'. The phrase was significant, at least to the thirteenth-century chronicler who devised it, for it suggested that this was more than simply a palace struggle; the north had become the centre of a reversionary interest.