The Iberian Peninsula was and is traditionally considered to be a region in the Mediterranean that was completely Christianized very early on. This status as unicum stems from the proselytizing in the times of the apostles, the uniqueness of the Middle Ages in its succession of Conquista and Reconquista, the strong development of the Counter-Reformation and the hegemony of an extremely conservative form of Catholicism in the modern age. The correspondence between the bishops of Hispania and the bishop of Rome or the pope between the middle of the 3rd and the end of the 7th century provide insight into the Hispanic conditions, which indicate a rather low degree of Christianization, and into a Relationship to Rome, which was mainly characterized by ignorance. In addition to the evidence of the historiographical transmission, the volume offers bibliographical information and an introduction to the history of the Roman and Visigothic Church.