thumb|upright=1.4|left|Scotland from the Matthew Paris map, c. 1250, showing Hadrian's Wall and above it the Antonine Wall, both depicted battlemented The long reign (900–942/3) of Causantín (Constantine II) is often regarded as the key to formation of the Kingdom of Alba. He was later credited with bringing Scottish Christianity into conformity with the Catholic Church. After fighting many battles, his defeat at Brunanburh was followed by his retirement as a Culdee monk at St. Andrews.. The period between the accession of his successor Máel Coluim I (Malcolm I) and Máel Coluim mac Cináeda (Malcolm II) was marked by good relations with the Wessex rulers of England, intense internal dynastic disunity and relatively successful expansionary policies. In 945, Máel Coluim I annexed Strathclyde as part of a deal with King Edmund of England, where the kings of Alba had probably exercised some authority since the later 9th century,. an event offset somewhat by loss of control in Moray. The reign of King Donnchad I (Duncan I) from 1034 was marred by failed military adventures, and he was defeated and killed by MacBeth, the mormaer of Moray, who became king in 1040.. MacBeth ruled for seventeen years before he was overthrown by Máel Coluim, the son of Donnchad, who some months later defeated MacBeth's step-son and successor Lulach to become King Máel Coluim III (Malcolm III)..
thumb|upright=14|left|scotland from the matthew paris map c 1250 showing hadrian's wall and above it the antonine wall both depicted battlemented the long reign (900–942/3) of causantín (constantine ii) is often regarded as the key to formation of the kingdom of alba he was later credited with bringing scottish christianity into conformity with the catholic church after fighting many battles his defeat at brunanburh was followed by his retirement as a culdee monk at st andrews the period between the accession of his successor máel coluim i (malcolm i) and máel coluim mac cináeda (malcolm ii) was marked by good relations with the wessex rulers of england intense internal dynastic disunity and relatively successful expansionary policies in 945 máel coluim i annexed strathclyde as part of a deal with king edmund of england where the kings of alba had probably exercised some authority since the later 9th century an event offset somewhat by loss of control in moray the reign of king donnchad i (duncan i) from 1034 was marred by failed military adventures and he was defeated and killed by macbeth the mormaer of moray who became king in 1040 macbeth ruled for seventeen years before he was overthrown by máel coluim the son of donnchad who some months later defeated macbeth's step-son and successor lulach to become king máel coluim iii (malcolm iii)