County Clare often referred to simply as Clare, is one of the original 26 counties within the Republic of Ireland and is also part of the Province of Munster. The county system has existed since the 16th century and counties form a significant part of local identity and culture in Ireland. Located on the mid-west coast of Ireland, Clare lies north of the River Shannon and covers a total area of 1,215 square miles (3,150 km˛). The biggest town and county seat is Ennis.
During the Early Middle Ages this area was part of the Kingdom of Connacht ruled by the Uí Fiachrach Aidhne, until it was annexed to the Kingdom of Munster to be settled by the Dalcassians in the mid-900s. It was renamed Thomond, meaning North Munster and produced Brian Boru during this period, one of the most noted High Kings of Ireland. From 1118 onwards the Kingdom of Thomond existed as its own petty kingdom, ruled by the O'Brien Clan.
There was some Norman influence during the 14th century due to battles with the de Clare's for control. Sovereignty of Thomond was handed over to the Tudors in 1543 and the area joined the Kingdom of Ireland as a county.
Clare's nickname is the Banner County, which may refer to a former local tradition of carrying banners at political meetings and public occasions. Reference: Wikipedia