Thomas A. Carlson (ed.), "Tigris Valley" in last modified January 14, 2014, http://syriaca.org/place/786 Tigris Valley The valley of the Tigris river. http://syriaca.org/place/786 David Wilmshurst The Ecclesiastical Organisation of the Church of the East, 1318-1913 111, 117-118 Gāzartā region