Nathanael Andrade, Assyrians, Syrians and the Greek Language in the late Hellenistic and Roman Imperial Periods (JNES 73 : 299-317)The analysis is complicated and there is no abstract, but here's an excerpt from the conclusion:
As stated in the analysis above, Greeks first began to distinguish between Syrians and Assyrians during the classical period. According to their perspective, the Syrians lived in the Levant west of the Euphrates river, and the Assyrians lived in the region of Mesopotamia extending east of it. The Greeks conceived of Syrians and Assyrians as sharing the same ethnic descent and cultural features, most notably the Aramaic language, but they arbitrarily placed them in regional categories. When the Hellenistic Greek kingdoms and (eventually) the Roman empire asserted authority over the Near East, they made this conceptual partitioning into a social fact maintained by imperial infrastructure. While they perceived Syrians and Assyrians (and Arameans) to be the same people, the Seleucids nevertheless defined Syria as a region west of the Euphrates and divided it into administrative districts. Roman authorities recognized this territory as the land inhabited by the Syrian ethnos, a social category distinct from the Assyrians who dwelled in Parthian and then Sasanian Mesopotamia.Requires a JSTOR subscription to access the full article. Cross-file under "Modern Aramaic Watch," sort of.
Such modes of differentiation were durable. During the mid-third century ce, one of the compilers of the Thirteenth Sibylline Oracle, himself a Syrian, lamented in Greek how Syrians had suffered the invasions of “Assyrian” hordes who had fought in the Persian ranks. This could have been an archaizing reference, but it also reflects the belief that Syrians lived in Roman territory and Assyrian counterparts in Persian ones.91 Sharing the same ancestral legacy, they nonetheless belonged to different social categories. Syrians were Assyrian, but they were a discrete, specific subset of them.
Despite such differentiation, Syrians of the Roman empire still could meaningfully conceive of themselves as Assyrians. While encapsulating a heterogeneous array of individuals who alternatively traced Greek, Assyrian, and other Near Eastern genealogies, they could emphasize how their ethnos in aggregate constituted the social legacy of the same ancient people from whom the Assyrians of the Parthian and Sasanian empires claimed to have originated. They could also reckon “Aramean” to be the common name for such Assyrians in the Aramaic language and not just for the inhabitants of the Sasanian Persian region called bēth Arāmāyē (otherwise known as Babylonia or Asūrestān). Even as Syria’s local cultures underwent tremendous cultural transformation, integrated Greek idioms, or generated “hybrid” cultural forms, Syrians still could produce narratives of an “Assyrian” past and vaunt Assyrian self-definition in ways that embedded their innovative and dynamic cultural expressions in a venerable pre-Hellenistic origin. Syrians adopted and adapted new practices amid imperial pressure, but they could continue to see themselves as traditional, as Assyrian, by constantly producing new perspectives on the history of the Assyrians, and reconceiving what Assyrian traditions were. Being Syrian and Assyrian was not a static phenomenon. It was a process of cultural creativity and productive memory, of forging links to a common Assyrian heritage while also identifying with a specific social unit to which many fellow Assyrians did not belong: the Roman imperial Syrian ethnos. How Syriac-speaking Christians fashioned distinct yet intersecting identifications as Syrians, Assyrians, or Arameans in late antiquity is a complex issue that cannot be explored here. But as this article has hopefully shown, how Greek-writing Syrians, or Assyrians, did so during the high Roman imperial period is a complex issue too.