Deir ez-Zor is the largest city in eastern Syria and the seventh largest in the country. Located on the banks of the Euphrates River 450 km (280 mi) to the northeast of the capital Damascus, Deir ez-Zor is the capital of the Deir ez-Zor Governorate. In the 2018 census, it had a population of 271,800.

Upper Mesopotamia constitutes the uplands and great outwash plain of northwestern Iraq, northeastern Syria and southeastern Turkey, in the northern Middle East. Since the early Muslim conquests of the mid-7th century, the region has been known by the traditional Arabic name of al-Jazira and the Syriac variant Gāzartā or Gozarto (ܓܙܪܬܐ). The Euphrates and Tigris rivers transform Mesopotamia into almost an island, as they are joined together at the Shatt al-Arab in the Basra Governorate of Iraq, and their sources in eastern Turkey are in close proximity.