The diocesan system of church government in Ireland is almost 900 years old. It was set up by the Synod of Rathbreasail in 1111 AD and modified by the Synod of Kells-Mellifont in 1152. The country is divided into four ecclesiastical provinces each headed by an archbishop. The provinces are in turn subdivided into suffragan dioceses each headed by a bishop. The only change in this system was the creation of the Diocese of Galway in 1831 following the abolition of the Wardenship of Galway.