I found this on Wikipedia:
EDIT: it´s about Nubia
WIKIPEDIA said:Christian Nubia
Around AD 350 the area was invaded by the Ethiopian kingdom of Axum and the kingdom collapsed. Eventually three smaller kingdoms replaced it: northernmost was Nobatia between the first and second cataract of the Nile River, with its capital at Pachoras (modern day Faras); in the middle was Makuria, with its capital at Old Dongola; and southernmost was Alodia, with its capital at Soba (near Khartoum). King Silko of Nobatia crushed the Blemmyes, and recorded his victory in a Greek inscription carved in the wall of the temple of Talmis (modern Kalabsha) around AD 500.
While bishop Athanasius of Alexandria consecrated one Marcus as bishop of Philae before his death in 373, showing that Christianity had penetrated the region by the fourth century, John of Ephesus records that a Monophysite priest named Julian converted the king and his nobles of Nobatia around 545. John of Ephesus also writes that the kingdom of Alodia was converted around 569. However, John of Bisclorum records that the kingdom of Makuria was converted to Roman Catholicism the same year, suggesting that John of Ephesus might be mistaken. Further doubt is cast on John's testimony by an entry in the chronicle of the Greek Orthodox Patriarch of Alexandria Eutychius, which states that in 719 the church of Nubia transferred its allegiance from the Greek Orthodox to the Coptic Church.
By the 7th century Makuria expanded becoming the dominant power in the region. It was strong enough to halt the southern expansion of Islam after the Arabs had taken Egypt. After several failed invasions the new rulers agreed to a treaty with Dogomba allowing for peaceful coexistence and trade. This treaty held for six hundred years. Over time the influx of Arab traders introduced Islam to Nubia and it gradually supplanted Christianity.
EDIT: it´s about Nubia