Achaemenid Assyria
Athura (Aramaic for Assyria) was a geographical area within the Persian Achaemenid Empire during the period of 539 BC to 330 BC. Although sometimes regarded as a satrapy, Achaemenid royal inscriptions list it as a dahyu, a concept generally interpreted as meaning either a group of people or both a country and its people, without any administrative implication.
It mostly incorporated the original Assyrian homeland in the upper Tigris, the middle and upper Euphrates, modern-day Syria (Eber-Nari) and part of south-east Turkey. The Neo-Assyrian Empire collapsed under the invasion of Iranian peoples in coalition with the Babylonians, Scythians and Cimmerians in the late 7th century BC, culminating in the Battle of Nineveh, and Assyria had fallen completely by 608 BC. Between 612 and 559 BC, Assyria was divided between the Median Empire to the east and the Neo-Babylonian Empire to the west. Both parts were subsumed into the Achaemenid Empire in 539 BC, and it has been argued that they constituted the satrapies of Media and Athura, respectively. In Herodotus' account the Ninth Tributary District comprised "Babylonia and the rest of Assyria", and excluded Eber-Nari.
Despite a few rebellions, Assyria functioned as an important part of the Achaemenid Empire. The Assyrian people were given the right to govern themselves throughout Achaemenid rule, and the Assyrian (Aramaic) language was used diplomatically by the Persians. Known for their combat skills, Assyrian soldiers (along with the Lydians) constituted the main heavy infantry of the Achaemenid empire's military. Due to the major destruction of Assyria during the fall of its empire, some scholars describe the area as an "uninhabited wasteland." Other Assyriologists, however, such as John Curtis and Simo Parpola, have strongly disputed this claim, citing how Assyria would eventually become one of the wealthiest regions among the Achaemenid Empire. This wealth was due to the land's great prosperity for agriculture that the Persians used effectively for almost 200 years. In contrast to the policy of the Assyrian Empire, the Achaemenid Persians did not intervene in the internal affairs of their ruling satrapies as long as they continued the flow of tribute and taxes back to Persia.
Read more about Achaemenid Assyria: Fall of The Assyrian Empire, Athura As Part of The Achaemenid Empire, Assyria After The Achaemenid Period