The next two kings (Kenneth III and Malcolm II) were his cousins and killed their respective predecessor to gain the throne.

The succession rule had the benefit of ensuring that there would always be an adult king on the throne, avoiding the usual problems of minority reigns.

The various kings had their lands and power bases in different areas of Scotland, preventing any single region from claiming full domination of the others.

The succession was often decided through acts of warfare and murder, resulting in early deaths and high casualty rates in the extended royal family.

[6] The alternation between the two royal lines seems to have been peaceful for a long time; Alfred P. Smyth regards this early phase as "a century of kingly coexistence".

[6] According to John of Fordun (14th century), Kenneth II of Scotland (reigned 971–995) attempted to change the succession rules, allowing "the nearest survivor in blood to the deceased king to succeed", thus securing the throne for his own descendants.

The two men then jointly conspired against him, convincing Lady Finella, daughter of Cuncar, Mormaer of Angus, to kill the king.

Entries in the Chronicles of the Picts and Scots, collected by William Forbes Skene, provide the account of Finnguala killing Kenneth II in revenge, but not her affiliation to Constantine or his cousins.

She approached him to proclaim her loyalty and invited him to visit her residence, whispering into his ear that she had information about a conspiracy plot.

Kenneth II gently touched the statue and "was shot through by arrows sped from all sides, and fell without uttering another word."

[9] Smyth dismisses the elaborate plotting and the mechanical contraption as mere fables, but accepts the basic details of the story, that the succession plans of Kenneth II caused his assassination.

[11] A later passage of John of Fordun mentions Finele as mother of Macbeth, King of Scotland (reigned 1040–1057), but this is probably an error based on the similarity of names.

The day following the death of Kenneth II, Constantine the Bald, son of King Cullen usurped the throne.

Constantine III reigned for a year and a half [18 months], "continually harassed by Malcolm and his illegitimate uncle, named Kenneth, a soldier of known prowess, who was his unwearied persecutor, and strove with his whole might to kill him, above all others.

[citation needed] John of Fordun had apparently listed this Kenneth as an illegitimate son of Malcolm I of Scotland.

An entry in the Chronicle of Melrose describes "King Constantine, Culen's son, ... slain by the sword" at the mouth of Almond in Tegalere.

According to it, Constantine and Kenneth, son of Malcolm met one day in Laudonia (Lothian), by the banks of the River Almond.

The guards of Constantine fled to Gryme (Kenneth III), "colleague" of their leader, allowing him to win the throne.

He learned of the death of his "uncle and the rest of his faithful friends", and returned to gather reinforcements for his cause — though he was defeated in his initial conflict against Gryme.

[20] A relevant entry from the Anglo-Saxon Chronicle confirms that the Danish fleet which regularly raided England departed in 1000.

[22] James Young Simpson, who had written several articles on archaeology, observed that there were contradictory accounts concerning the location of Constantine's death.

The "Nomina Regum Scottorum et Pictorum", discovered by Robert Sibbald at the St Andrews Cathedral Priory, places the death sites of both Domnall mac Ailpín and Constantine III at Rathveramoen (Rathinveramon), which etymologically derives from "Rath Inver Amoen", the ráth at the mouth of the Amoen/Amon (the Almond) – viz., the fortress Bertha in Perth,[23] located at the mouth of the Almond.

[27] Alex Woolf points out that the Chronicle of the Kings of Alba reports another location for the death of Domnall mac Ailpín: the palace of Cinnbelathoir, which was probably the same as the "Bellathor", mentioned alongside "Rigmonath" as the major settlements of their time.

He noted an extant transcription of the Cat Stane's text, reading: "IN HOC TUM- JAC – CONSTAN- VIC- VICT".

[23][30] The idea went that the Cat Stane was erected as a memorial for Constantine, at the location where the man lost his life in battle.

[23] Simpson strongly opposed this theory, finding it unlikely that such a monument would be erected for Constantine the Bald, a king who fell in a civil war, with no family legacy, and who was treated with contempt by primary sources.

Anderson suggested that this would be the area from Stirling to Tentsmuir (Abertay Sands), the traditional Scottish boundary with "Danish Northumbria" (Jórvík).

The length of his reign (18 months) confirms that Constantine is the failed "non-king" intended, a king surrounded by weak men.

The Almond flows into the Tay in a location not far from Scone, also recorded as the place of death of a previous king, Domnall mac Ailpín (reigned 859–862).