The Kingdom of Aksum, the first known kingdom of great power to rise in Ethiopia, rose during the first century AD. The Persian religious figure Mani listed Axum with Rome, Persia, and China as one of the four great powers of his time. It was in the early 4th century that a Syro-Greek castaway, Frumentius, was taken to the court and over time changed King Ezana to Christianity, making Christianity Ethiopia's religion. For this, he received the title "Abba Selama". At different times, including a time in the 6th century, Axum ruled most of modern-day Yemen just across the Red Sea.