The term 'Irish Kingdom' can be broken down into two crossword solutions: ULSTER (6 letters) and Irish (5 letters). ULSTER is a province in the north of Ireland, which was historically part of the Kingdom of Ireland. The Kingdom of Ireland was a sovereign state that existed from 1541 until 1800, when it was merged with the Kingdom of Great Britain to form the United Kingdom of Great Britain and Ireland. Irish is the name of the language spoken by the majority of people in Ireland.