The Christian Nubian kingdoms, which will survive for many centuries, achieve their peak of prosperity and military power in the ninth and tenth centuries.

However, Muslim Arab invaders, who in 640 had conquered Egypt, pose a threat to the Christian Nubian kingdoms.

Most historians believe that Arab pressure forced Nobatia and Makuria to merge into the kingdom of Dongolah sometime before 700.

Although the Arabs had soon abandoned attempts to reduce Nubia by force, Muslim domination of Egypt often makes it difficult to communicate with the Coptic patriarch or to obtain Egyptian- trained clergy.

As a result, the Nubian church becomes isolated from the rest of the Christian world.