Province (pop., 2002 prelim.: 464,050), northwestern Ireland. It is composed of the counties of Galway, Leitrim, Mayo, Roscommon, and Sligo and has an area of 6,611 sq mi (17,122 sq km). An ancient kingdom, Connacht was Christianized by St. Patrick in the 5th century. Dominated from the 11th century by the O'Connors of Roscommon, it endured an Anglo-Norman invasion in the 12th century.