One of the oldest cities in Upper Mesopotamia, the area of Ras al-Ayn has been inhabited since at least the Neolithic age ( 8,000 BC). Later known as the ancient Aramean city of Sikkan, the Roman city of Rhesaina, and the Byzantine city of Theodosiopolis, the town was destroyed and rebuilt several times, and in medieval times was the site of fierce battles between several Muslim dynasties. With the 1921 Treaty of Ankara, Ras al-Ayn became a divided city when its northern part, today's Ceylanpınar, was ceded to Turkey.