Complex sentence: Brian, Tadhg, and Aodh formed an alliance, and in 1258 they met near a ruined Geraldine castle at Belleek, County Fermanagh on the Erne, where Brian was confirmed as High King of Ireland and Aodh's overlordship of Breifne was accepted.
Split into simpler sentences: Brian, Tadhg, and Aodh formed an alliance, and in 1258 they met near a ruined Geraldine castle at Belleek on the Erne. Here Brian was confirmed as High King of Ireland and Aodh's overlordship of Breifne was accepted.