Here is a link to a fascinating article in Smithsonian Magazine about a church in Ethiopia that has been located by archaeologists. This discovery confirms what Ethiopian tradition has always maintained, that Christianity was in Eastern Africa very early in its history.
The church is located in the town of Beta Samati, which was part of the kingdom of Aksum, one of the most influential ancient kingdoms of the world.
Here is a map showing the location of Beta Samati, in northern Ethiopia, near the border of Eritrea: