 Ímar 's probable uncle , Sitriuc , ruled Dublin for almost fifty years between <unk> and 1036 . There is reason to suspect that the latter 's realm included Mann by the second or third decade of the eleventh century . His reign in Dublin was finally put to an end by Echmarcach mac Ragnaill ( died 1064 / 1065 ) , who drove Sitriuc from the coastal town and claimed the kingship for himself . Previously , Sitriuc seems to have been closely aligned with Knútr <unk> ( died 1035 ) , ruler of the kingdoms of England , Denmark , and Norway . Knútr 's apparent authority in the Irish Sea region , coupled with Sitriuc 's seemingly close connections with him , could account for the remarkable security enjoyed by Sitriuc during Knútr 's reign . It is possible that Echmarcach had been bound from taking action against Sitriuc whilst Knútr held power , and that the confusion caused by the latter 's death in 1035 enabled Echmarcach to exploit the situation and seize control of the Irish Sea region . Although there is no direct evidence that Echmarcach controlled Mann by this date , Sitriuc does not appear to have taken refuge on the island after his expulsion from Dublin . This seems to suggest that the island was outside Sitriuc 's possession , and may indicate that Mann had fallen into the hands of Echmarcach sometime before . In fact , it is possible that Echmarcach used the island to launch his takeover of Dublin . 
