Tur Abdin (; ; ) is a hilly region situated in southeast Turkey, including the eastern half of the Mardin Province, and Şırnak Province west of the Tigris, on the border with Syria and famed since Late Antiquity for its Christian monasteries on the border of the Roman Empire and the Sasanian Empire. The area is a low plateau in the Anti-Taurus Mountains stretching from Mardin in the west to the Tigris in the east and delimited by the Mesopotamian plains to the south. The Tur Abdin is populated by more than 80 villages and nearly 70 monastery buildings and was mostly Syriac Orthodox until the early 20th century. The earliest surviving Christian buildings date from the 6th century.