Answer :
The Coptic religion, which was a branch of christianity, was declared, also giving birth to the legend of prester john, which I would look up.
Answer: Christianity.
Explanation:
Since the early 1st millennium CE, Christianity had been brought to Aksum territory (today´s Ethiopia, Eritrea, Djibouti, Somalia, and Somaliland) by traders and Egyptian missionaries. Eventually, under Ezana (fl. 320–360) Aksum embraced Christianity, due to the the kingdom´s significant trade relationships with the North African territories of the Roman Empire.