Connacht ( KON-awt, KON-ə(kh)t; Irish: Connacht [ˈkɔn̪ˠəxt̪ˠə] or Cúige Chonnacht [ˌkuːɟə ˈxɔn̪ˠəxt̪ˠ]), or Connaught, is one of the provinces of Ireland, in the west of Ireland. Until the ninth century it consisted of several independent major Gaelic kingdoms (Lúighne, Uí Maine, and Iar Connacht).
Between the reigns of Conchobar mac Taidg Mór (died 882) and his descendant, Aedh mac Ruaidri Ó Conchobair (reigned 1228–33), it became a kingdom under the rule of the Uí Briúin Aí dynasty, whose ruling sept adopted the surname Ua Conchobair. At its greatest extent, it incorporated the often independent Kingdom of Breifne, as well as vassalage from the lordships of western Mide and west Leinster. Two of its greatest kings, Tairrdelbach Ua Conchobair (1088–1156) and his son Ruaidri Ua Conchobair (c. 1115–1198) greatly expanded the kingdom's dominance, so much so that both became Kings of Ireland.
The Kingdom of Connacht collapsed in the 1230s because of civil war within the royal dynasty, which enabled widespread Hiberno-Norman settlement under Richard Mór de Burgh, 1st Baron of Connaught, and his successors. The Norman colony in Connacht shrank from c. 1300 to c. 1360, with events such as the 1307 battle of Ahascragh (see Donnchad Muimnech Ó Cellaigh), the 1316 Second Battle of Athenry and the murder in June 1333 of William Donn de Burgh, 3rd Earl of Ulster, all leading to Gaelic resurgence and colonial withdrawal to towns such as Ballinrobe, Loughrea, Athenry, and Galway. Well into the 16th century, kingdoms such as Uí Maine and Tír Fhíacrach Múaidhe remained beyond English control, while many Norman families such as de Burgh, de Bermingham, de Exeter, de Staunton, became entirely Gaelicised. Only in the late 1500s, during the Tudor conquest of Ireland, was Connacht shired into its present counties.
Connacht's population was 1.4 million before the Great Famine of the 1840s, which began a 120-year decline to under 400,000. The province had a population of 550,000 at the 2016 census.
British cultural imperialism was weaker in the west of Ireland, and Connacht today has the highest number of Irish language speakers among the four Irish provinces. Currently, the total percentage of people who consider themselves as Irish speakers in Connacht is 39.8% (more than 202,000 persons). There are Gaeltacht areas in Counties Galway and Mayo.
The province of Connacht has no official function for local government purposes, but it is an officially recognised subdivision of the Irish state. It is listed on ISO-3166-2 as one of the four provinces of Ireland and "IE-C" is attributed to Connacht as its country sub-division code. Along with counties from other provinces, Connacht lies in the Midlands–North-West constituency for elections to the European Parliament.