https://en.wikipedia.org/wiki/Sigtrygg_Silkbeard

Sigtrygg II Silkbeard Olafsson was a Hiberno-Norse king of Dublin of the Uí Ímair dynasty. He was caught up in the abortive Leinster revolt of 999–1000, after which he was forced to submit to the King of Munster, Brian Boru. His family also conducted a double marriage alliance with Boru, although he later realigned himself with the main leaders of the Leinster revolt of 1012–1014. He has a prominent role in the 12th-century Irish Cogadh Gaedhil re Gallaibh and the 13th century Icelandic Njal's Saga, as the main Norse leader at the Battle of Clontarf in 1014.

Sigtrygg's long reign spanned 46 years, until his abdication in 1036.[4] During that period, his armies saw action in four of the five Irish provinces of the time. In particular, he conducted a long series of raids into territories such as Meath, Wicklow, Ulster, and perhaps even the coast of Wales. He also came into conflict with rival Norse kings, especially in Cork and Waterford.

He went on pilgrimage to Rome in 1028 and is associated with the foundation of Christ Church Cathedral in Dublin. Although Dublin underwent several reversals of fortune during his reign, on the whole trade in the city flourished. He died in 1042.