Complex sentence: During this time, two-thirds of Ireland was governed by the Irish Catholic Confederation, also known as the "Confederation of Kilkenny", which was based in Kilkenny and formed by Irish Catholic nobles, clergy and military leaders after the Irish Rebellion of 1641.
Split into simpler sentences: During this time, two-thirds of Ireland was governed by the Irish Catholic Confederation, also known as the "Confederation of Kilkenny", which was based in Kilkenny. This was formed by Irish Catholic nobles, clergy and military leaders after the Irish Rebellion of 1641.