Deir ez-Zor is situated 85 km to the northwest of the archaeological remains of Dura-Europos and 120 km northwest of the remains of the ancient city of Mari.
Dura-Europos ("Fort Europos") was a Hellenistic and Roman walled city built on an escarpment ninety meters above the right bank of the Euphrates river. It is located near the village of Salhiyé, in today's Syria.
It was founded in 303 BC by the Seleucids on the intersection of an east-west trade route and the trade route along the Euphrates. The new city, commemorating the birthplace of Alexander's successor Seleucus I Nicator, controlled the river crossing on the route between his newly founded cities of Antioch and Seleucia on the Tigris. Its rebuilding as a great city built after the Hippodamian model, with rectangular blocks defined by cross-streets ranged round a large central agora, was formally laid out in the 2nd century BC.
The traditional view of Dura-Europos as a great caravan city is becoming nuanced by the discoveries of locally made manufactures and traces of close ties with Palmyra.
During the later second century BC it came under Parthian control and in the first century BC, it served as a frontier fortress of the Arsacid Parthian Empire, with a multicultural population, as inscriptions in Greek, Latin, Aramaic, Hebrew, Syriac, Hatrian, Palmyrenean, Middle Persian and Safaitic Pahlavi testify. It was captured by the Romans in 165 and abandoned after a Sassanian siege in 256-257. After it was abandoned, it was covered by sand and mud and disappeared from sight.
Mari (modern Tell Hariri) was an ancient Sumerian and Amorite city, located 11 kilometers north-west of the modern town of Abu Kamal on the western bank of Euphrates river, some 120 km southeast of Deir Ez-Zor, Syria. It is thought to have been inhabited since the 5th millennium BC, although it flourished from 2900 BC until 1759 BC, when it was sacked by Hammurabi.
Mari had been inhabited since the 5th millennium BC, but the real significance of the city was during the third and second millennia BC. The inhabitants of Mari were a Semitic people, thought to be part of the same Eblaite and Akkadian migration.
The Mari Tablets are a large group of tablets discovered by French archaeologists in the 1930's. More than 23,000 tablets were found, which gave information about the kingdom of Mari including the customs of the Mari kingdom, as well as giving names of people who lived during that time.