Sasanian Persia used deportation as a standing instrument of imperial development. Shapur I's campaigns against Rome — culminating in the capture of Antioch and the defeat and capture of the emperor Valerian in 260 CE — produced very large numbers of prisoners and civilians whom he settled across his empire, as his own inscription at Naqsh-e Rustam records. Roman captives were used to build and populate new royal foundations, including Bishapur in Fars and Gundeshapur in Khuzistan, and to construct bridges and dams; deportees were given agricultural land and housing, kept their Christianity, and formed the nucleus of the Christian communities of Sasanian Iran, a point stressed in the Syriac Chronicle of Seert. Shapur II continued the practice in the fourth century. Iranian policy resembled the Assyrian and Achaemenid pattern in aiming at productive resettlement rather than destruction, and the deportees' skills — masonry, engineering, weaving — were the point. No source gives usable totals.
Sasanian kings, above all Shapur I and later Shapur II, carried off the populations of captured Roman cities in Syria, Cilicia and Cappadocia and settled them in new and existing cities of the Iranian plateau and Mesopotamia
No defensible denominator exists. The deportations spanned nearly a century and a half and many separate campaigns, and the affected cities — Antioch, Dura-Europos, Amida, and the towns of Cilicia and Cappadocia — have no agreed populations; estimates for Antioch alone range from about 100,000 to 300,000. The evidence is Shapur I's Res Gestae Divi Saporis inscription, later Syriac and Greek chronicles, and the archaeology of the Iranian foundation cities such as Gundeshapur, none of which supports an aggregate.
No death toll is recoverable, and none is implied by the policy: deportees were valued as builders, craftsmen and farmers and were settled with land and housing. Deaths occurred in the sack of cities such as Antioch, but no source quantifies them.
Shapur I's own inscription and the Syriac and Arabic sources summarised by Encyclopaedia Iranica record the use of deported Roman captives to build cities, bridges and dams in Iran.
Iran, Turkey