In the Nile Valley, from the First Cataract south to the area around Khartoum (the region formerly known as Nubia), there was a considerable Christian community from the late 6th to at least the 15th cent. There may have been Christians in north Nubia in the 4th cent., but the formal introduction of Christianity dates from the arrival of missionaries sent by the Emp. Justinian and his wife Theodora in 543. The rulers of the three kingdoms in the area were converted, soon to be followed by the greater part of the population; by c.580 all three kingdoms were officially Christian. The Nubian Churches were Monophysite, and bishops were appointed by the Patr. of Alexandria. In 1172 the Fatimid dynasty in Egypt, which had been tolerant of Christianity and on good terms with Nubia, was overthrown. Both Church and State in Nubia declined. In the 15th cent. there were still Christian kings and bishops in parts of Nubia, but by the early 16th cent. Muslim political control was complete and the Christian community faded away. For modern Christianity, see Sudan, Christianity in.