Religion in Medieval England includes all forms of religious organisation, practice and belief in England, between the end of Roman authority in the fifth century and the advent of Tudor dynasty in the late fifteenth century. The collapse of Roman authority brought about the end of formal Christian religion in the east of what is now England as Anglo-Saxon invaders took control of large sections of the island. The movement towards Christianity began again in the late sixth and seventh centuries. Pope Gregory I sent a team of missionaries who gradually converted most of the Anglo-Saxon kingdoms, while Scots-Irish monks were active in the north of England. The process was largely complete by the end of the seventh century, but left a confusing and disparate array of local practices and religious ceremonies. The Viking invasions of the eighth and ninth centuries reintroduced paganism to North-East England, leading in turn to another wave of conversions.