Axum Empire

Aksum was a remarkably tolerant place for its time, as followers of earlier African religions were not persecuted.

An excerpt from the article 20 facts about Axum Empire
During archeological excavations near the village of Edaga Rabu, researchers found the ruins of the Beta Samati (meeting house) building - an early Christian church - where both Christian and pagan artifacts were found. In the 6th century, the first Muslims from the area of Mecca also found refuge in Aksum.