Brian Boru makes an expedition to the north to take hostages from the northern states.
1005
Brian Boru makes a second expedition to the north to take hostages from the northern states: during this expeidion, he visited Armagh, making an offering of twenty ounces of gold to the church and confirming to the apostolic see of Saint Patrick, ecclesiastical supremacy over the whole of Ireland (as recorded in the Book of Armagh).[3]
1006
Brian Boru makes a triumphal progress around Leath Cuinn, taking hostages from every northern state, thus demonstrating he was undisputed King of Ireland.[3]
Brian Boru campaigned against the Vikings of Dublin under their King Sihtric and North Leinster led by Máel Mórda Mac Murchada, following attacks by them on Brian's ally Máel Sechnaill mac Domnaill.
1014
23 April: Battle of Clontarf, at which the Vikings and men of North Leinster were defeated by Brian Boru, who was killed in the battle.[4]
Niall mac Eochada defeats the Dublin Norse at sea.[7]
Death of Mael Seachnaill II, Overking of the Uí Néill, who had reigned since 980, [2] and who became King of Ireland on the death of Brian Boru in 1014 and ruled until his death.[8]
1024 and 1026
Niall mac Eochada invades Dublin and take hostages.[6]
1030s
1030
Death of Gormflaith (b. 960), daughter of Murchad mac Find, King of Leinster, and third wife of Brian Ború.
1036
Death of Sigtrygg Silkbeard Olafsson, son of King Olaf Cuaran (also called Kvaaran) and Gormflaith. He was the leader of the Vikings at the Battle of Clontarf in 1014. (but see also 1042)
Death of Diarmait mac Mail na mBo, a king of Leinster and a contender for the title of High King of Ireland. He was one of the most important and significant Kings in Ireland in the pre-Norman era.