Asoristan (Middle Persian: 𐭠𐭮𐭥𐭥𐭮𐭲𐭭 Asōristān, Āsūristān) was the name of the Sasanian province of Assyria and Babylonia from 226 to 637.

The region was also called several other names, mostly relating to its Assyrian inhabitants: Assyria, Athura, Bēṯ Nahren (Classical Syriac: ܒܝܬ ܢܗܪܝܢ lit.

[1] The name Assyria, in the form Asōristān, was shifted to include what had been ancient Babylonia by the Parthians, and this continued under the Sasanians.

Asōristān, Middle Persian "land of Assyria",[1] was the capital province of the Sasanian Empire and was called Dil-ī Ērānshahr, meaning "Heart of Iran".

The Parthians had exercised only loose control at times, allowing for a number of Assyrian kingdoms to flourish in Upper Mesopotamia in the form of independent Osroene, Adiabene, Beth Nuhadra, Beth Garmai and the partly Assyrian state of Hatra, and Assyriologists such as Georges Roux and Simo Parpola opine that ancient Assur itself may have been independent during this time.

Asōristān was dissolved by 639 AD, bringing an end to over 3000 years of Assyria as a geopolitical entity, although it remained an ecclesiastical province within Syriac Christianity.

Nabateans and Arameans dwelt in the far southwestern deserts, and minorities of Persians, Mandeans, Armenians and Jews lived throughout Mesopotamia.

The Greek element in the southern cities, still strong in the Parthian period, was absorbed by the Assyrians in Sasanian times.

The majority of the population was Assyrian, Jewish, and Mandaean, speaking Akkadian-influenced Eastern Aramaic languages, some of which still survive as Northeastern Neo-Aramaic.

[8] The native Assyrians played a very active role in the province and were found in the administrative class of society as army officers, civil servants, and feudal lords.

Aside from the liturgical scriptures of these religions which exist today, archaeological examples of all three of these dialects can be found in the collections of thousands of Aramaic incantation bowls—ceramic artifacts dated to this era—discovered in Iraq, northeast Syria and southeast Turkey.

Temples were still being dedicated to Ashur, Shamash, Ishtar, Sin, Hadad, Dumuzid, Nergal, Bel and Ninurta in Assur, Arbela, Edessa, Amid, Nohadra, Kirkuk, Sinjar, Nineveh Plains, and Harran among other places, during the 3rd and 4th centuries, and traces would survive into the 10th century in remote parts of Mesopotamia.

The Jewish–Roman wars, the Crisis of the Third Century, and Rome's conversion to Christianity all led to an increase in Jewish immigration to Asoristan, and the region became the main center of Judaism in Late Antiquity.

The Sasanian state religion, Zoroastrianism, was largely confined to the Iranian administrative class, and did not filter down to the Assyrian-Babylonian population.