Kleisoura (Byzantine district)
A Kleisoura (Greek κλεισούρα, " boundary, hermitage " ) designated in the Byzantine Empire a fortified mountain pass and it sheltered military border district. From the 7th century, the term was used generally for the districts on the borders of themes, especially along the eastern border of the Byzantine to Islamic caliphate along the Taurus Mountains - Antitaurus line ( in the West was at first only the theme of Strymon a Kleisoura ). A Kleisoura or Kleisourarchia was an independent predictor under the command of a Kleisourarches (Greek: κλεισουράρχης ). Gradually almost all Kleisourai were elevated to the status of themes, so that the term from the 10th century fell into disuse ( in the late Byzantine period had Droungos a similar meaning ). The Islamic counterpart to the Kleisourai was in Syria and Mesopotamia, the al - Thughūr.