What is the Christian kingdom in the mountains of East Africa?

The Christian Kingdom in the Mountains of East Africa is a city called Axum (it is also spelled Aksum) in Ethiopia. It was the earliest Christian Empire in the world.

This historical site, from the tenth to first century BC, was the capital of the Auximite Empire, considered to be one of the last great empires. Christianity arrived in the fourth century to Axum, and it is known as the holiest city in the Ethiopian Orthodox Faith. Though not as grand now, the city still exudes a deeply religious reverence from both Ethiopian Orthodox and Sunni Muslim citizens, who are the guardians of the city's most sacred artifact, the reputed Ark of the Covenant.