Councils of Toledo
From the 5th century to the 7th century AD, about thirty synods, variously counted, were held at Toledo (Concilia toletana) in what would come to be part of Spain. The earliest, directed against Priscillianism, assembled in 400. The "third" synod of 589 marked the epoch-making conversion of King Reccared from Arianism to orthodox Chalcedonian Christianity. The "fourth", in 633, probably under the presidency of the noted Isidore of Seville, regulated many matters of discipline and decreed uniformity of liturgy throughout the kingdom. The British Celts of Galicia accepted the Latin rite and stringent measures were adopted against baptized Jews who had gone back to their former faith. The "twelfth" council in 681 assured to the archbishop of Toledo the primacy of Hispania (present Iberian Peninsula). As nearly one hundred early canons of Toledo found a place in the Decretum Gratiani, they exerted an important influence on the development of ecclesiastical law.
The later synod of 1565 and 1566 concerned itself with the execution of the decrees of Trent; and the last council of Toledo, that of 1582 and 1583, was so guided in detail by Philip II that the pope ordered the name of the royal commissioner to be expunged from the acts.
The seventh century is sometimes called, by Spanish historians, the Siglo de Concilios, or "Century of Councils".