The Kingdom of Aksum, covering much of modern-day Eritrea and the Tigray Region in northern Ethiopia, arose somewhere around the first or second centuries. The Aksumites erected a number of large stelae, which served a religious purpose in pre-Christian times. Over 200 years after the kingdom's formation, it adopted Christianity under King Ezana. Eritrea was also one of the first Islamic settlements in Africa, as a group of Muslims facing persecution in Mecca migrated to the Kingdom of Aksum. Islam spread to Ethiopia and Eritrea around 615 AD with the arrival of Uthman ibn Affan, one of the "Sahabah" (companions) of the Islamic prophet Muhammad. Uthman had been driven out of Saudi Arabia and found shelter at Axum in the Tigray Region of Ethiopia under the protection of the Axumite king, Aṣḥama ibn Abjar.