The origins of Christianity in the area comprising modern Romania are uncertain. The Roman occupation of the region (Dacia) ended in a.d. 275. There may have been Christians among the Roman legions and colonists. By the fourth century, Christian communities had grown up in the Dacian regions as missionaries from centers on the right bank of the Danube carried on an expanding ministry. Shortly after this period, the waves of barbarian invasions began, and not until the medieval epoch can one speak of a full-fledged Christian church in Romania. With the establishment of the two principalities of Moldavia and Wallachia, organized Christianity began the thread which leads to the present. The metropolitanate of Ungro-Vlahia was founded in 1359, that of Moldavia in 1401; their recognition by the patriarchate of Constantinople signaled an acceptance of important religious and political developments rather than their inception.