Alba
The ruler of Alba at the beginning of 943 was King Constantine II (Constantine the Middle-Aged), who had ruled since 900. This year, King Malcolm I (Malcolm the Dangerous Red) would take over.
Deheubarth
The ruler of Deheubarth was King Hywel ap Cadell ap Rhodri (Hywel the Good), who had ruled since 920 and would continue to do so until 950.
England
The ruler of England was King Eadmund I (Eadmund the Magnificent), who had ruled since 939 and would continue to do so until 946.
Jórvík
The ruler of Jórvík during this time was either King Olaf Sigtryggsson or King Ragnall Guthfrithson, the exact year of the succession is unknown.
Strathclyde
The ruler of Strathclyde at this time was likely to have been King Dyfnwal map Owain.