Thomas A. Carlson (ed.), "al-Thaghr" in last modified June 30, 2014, http://syriaca.org/place/567 al-Thaghr الثغر الثَغْر The border area of northern Syria and Mesopotamia between the Byzantine Empire and the caliphate. Attestation of name الثَغْر in the Muʿjam al-buldān of Yāqūt al-Ḥamawī. http://syriaca.org/place/567 كتاب اللؤلؤ المنثور في تاريخ العلوم والأداب السريانية 511 The Scattered Pearls: A History of Syriac Literature and Sciences 569 Muʿjam al-buldān Yāqūt al-Ḥamawī II:93