In the 4th century, Papa, Bishop of the Capital (Seleucia-Ctesiphon), takes the first step towards the primacy of his see. Under the Sassanid kings, especially Shapur II, the Persian Church is fiercely persecuted. Later synods confirm Seleucia-Ctesiphon as metropolis, and at last in 424 the way is prepared for the heresy which will overwhelm the Persian Church, by a declaration of independence of any Western authority.