Alba
The ruler of Alba was King Malcolm II (Malcolm the Destroyer), who had ruled since 1005 and would continue to do so until 1034.
Deheubarth
King Edwin ab Einion ab Owain ruled jointly with his brother, King Cadell ab Einion ab Owain .
England
The ruler of England was King Æthelræd II (Æthelred the Unready), who had ruled since 978 and would continue to do so until 1013.
Gwynedd
The ruler of Gwynedd was King Aeddan ap Blegywryd, who had ruled since 1005 and would continue to do so until 1018.
Moray
The ruler of Moray was Mormaer Findláech mac Ruaidrí (probably, the start of his reign is shrouded in mystery).
Strathclyde
The ruler of Strathclyde at this time was likely to have been King Owain Foel.