Rhesaina (Rhesaena) (Ancient Greek: Ρέσαινα and Ρεσαίνα) was a city in the late Roman province of Mesopotamia Secunda and a bishopric that was a suffragan of Dara. Rhesaina (Rhesaena, Resaena – numerous variations of the name appear in ancient authors) was an important town at the northern extremity of Mesopotamia, near the sources of the Chaboras (now the Khabur River. It was on the way from Carrhae to Nicephorium, about eighty miles from Nisibis and forty from Dara. Nearby, Gordian III fought the Persians in 243, at the battle of Resaena. It is now Ra's al-'Ayn, Syria.