There are several distinct Gaelic origins of the surname Breen, as both Mac Braoin and O Braoin, from braon, meaning "moisture", or "drop". The Mac Braoin were originally located near the town of Knocktopher in Co. Kilkenny, but migrated to Wexford after the Anglo-Norman invasions in the twelfth and thirteenth centuries. Co. Wexford is still the area of the country in which the surname is most common, though a separate Wexford sept, the O Briain, also had their surname anglicised as Breen. These were descended from Bran Finn, son of Lachta, King of Munster, and uncle of Brian Boru. However, the O'Breens rulers of Brawney, a territory near Athlone in counties Offaly and Westmeath, were the most powerful of the name in the middle ages; as they lost power the name mutated, and many in the area are now to be found as O'Briens. The surname is now also quite common in north Connacht, Co. Fermanagh, and in Co. Kerry.