Interpretation
During the 10th century, there were dynastic conflicts in Scotland between two rival lines of royalty. One descended from Causantín mac Cináeda (Constantine I, reigned 862-877), the other from his brother Áed mac Cináeda (reigned 877-878). John of Fordun claims that Kenneth II of Scotland (reigned 971-995) attempted to establish new succession rules, which would limit the right to the throne to his own descendants. Excluding all other claimants. While Constantine III of Scotland (reigned 995-997) did manage to rise to the throne, he was the last known descendant of Áed. With his death, the rivalry between descendants of Causantin and Áed gave way to a rivalry between two new royal lines. Both descended from Causantin.
One line descended from Kenneth II and was represented by his son Malcolm II. The other line descended from his brother Dub, King of Scotland (reigned 962-967) and was represented by Kenneth III. Neither Constantine III, nor Kenneth III were able to extend their control to Cumbria. Which likely served as a stronghold and powerbase for Malcolm II. He was the legitimate heir according to the succession rules of Kenneth II. When Malcolm II managed to kill Kenneth III, it signified the triumph of his line. He continued to rule to 1034, enjoying a long reign. Managing to leave the throne to his own descendants.
But the rivalry between the two lines survived Kenneth III. In 1033, Malcolm II killed a descendant of Kenneth III. Gruoch, another descendant of Kenneth III was the consort of Macbeth, King of Scotland (reigned 1040–1057). Whose rival Duncan I (reigned 1034–1040) was the grandson and heir of Malcolm II. They were continuing the bitter feud which had started in the previous century.
The contemporary kings of Strathclyde were also involved in the feud, though it uncertain whether they had dynastic connections with the various Scottish rival lines. A theory that they represented another line of descendants of Donald II of Scotland (reigned 889-900) was based on the idea that Owen I of Strathclyde (d. 937) was son to this king.
Read more about this topic: Kenneth III Of Scotland