[1] As the western gate to central Mesopotamia, it was fortified by the Sasanian ruler Shapur I (r. 241–272) to shield his capital, Ctesiphon, from the Roman Empire.

[1] After his decisive victory over the Roman emperor Gordian III at the Battle of Misiche in 244, Shapur renamed the town to Peroz-Shapur (Pērōz-Šāpūr or Pērōz-Šābuhr, from Middle Persian: 𐭯𐭥𐭩𐭥𐭦𐭱𐭧𐭯𐭥𐭧𐭥𐭩, meaning "victorious Shapur"; in Parthian: 𐭐𐭓𐭂𐭅𐭆𐭔𐭇𐭐𐭅𐭇𐭓, romanized: prgwzšhypwhr; in Imperial Aramaic: פירוז שבור).

[5] When Ali ibn Abi Talib (r. 656–661) passed through the city, he was warmly welcomed by ninety-thousand Jews who then lived there, and he "received them with great friendliness.

[8] Ibn Abi Waqqas initially considered Anbar as a candidate for the location of one of the first Muslim garrison towns, but the fever and fleas endemic in the area persuaded him otherwise.

[8] According to medieval Arabic sources, most of the inhabitants of the town migrated north to found the city of Hdatta south of Mosul.

[8] Abu'l-Abbas as-Saffah (r. 749–754), the founder of the Abbasid Caliphate, made it his capital in 752, constructing a new town half a farsakh (c. 2.5 kilometres (1.6 mi)) to the north for his Khurasani troops.

[8][10] The Abbasids also dug the great Nahr Isa canal to the south of the city, which carried water and commerce east to Baghdad.

In 927, the Qarmatians under Abu Tahir al-Jannabi sacked the city during their invasion of Iraq, and the devastation was compounded by another Bedouin attack two years later.

The remains include traces of the late medieval wall, a square fortification, and the early Islamic mosque.