A paleogenomic time transect of the city of Rome in Central Italy (28) identified an ancestry shift toward the Near East during the Imperial period (27 BCE to 300 CE) but was unable to localize the origin of the migrants driving this phenomenon. We sought to identify the geographic sources of these Imperial-era Romans by coanalyzing the data from Italy with data from the Southern Arc.
Unexpectedly, the ancestry of the sample of people whose genomes were analyzed who lived around Rome in the Imperial period was almost identical to that of Roman and Byzantine individuals from Anatolia in both their mean (Fig. 3A) and pattern of variation (Fig. 3B), whereas Italians before the Imperial period had a very different distribution (28, 29). We clustered diverse Roman, Byzantine, and medieval individuals and their immediate predecessors without any knowledge of their population labels and found that the Italian and Anatolian individuals clustered together with those of pre-Roman Anatolia, whereas pre-Imperial people around the city of Rome were systematically different (Fig. 3C). This suggests that the Roman Empire in both its shorter-lived western part and the longer-lasting eastern centered on Anatolia had a diverse but similar population plausibly drawn, to a substantial extent, from Anatolian pre-Imperial sources.
In an irony of history, although the Roman Republic prevailed in its existential military struggle against the Anatolians rallied by Mithridates VI of Pontus during the first century BCE, the final incorporation of Anatolia into the Roman Empire and the increased connectivity that ensued may have set the stage for the very same Anatolians to become the demographic engine of Imperial Rome itself. This recreated, in historical time, the mythical journey of Aeneas and his Trojan exiles from Anatolia to the shores of Italy.
The Southern Arc was also a recipient of many immigrants from outside the region in the Historical period, such as two individuals sampled in Samsun in the Black Sea region from the Roman era in the second to third centuries CE (17). These individuals have both Eastern European hunter-gatherer and some East Eurasian ancestry that contrasts them with the local population of the Black Sea region that had been stable since the Chalcolithic (30), across the Early Bronze Age transition at Amasya, and down to the time of the Kingdom of Pontus (first century BCE).
Broad genetic stability in Anatolia during the Roman-Byzantine period did not mean isolation, as outliers of likely Levantine, Northern European or Germanic, and Iberian origin are detected in the Marmara region (in the Basilica of Nicaea or present-day Iznik and the Virgin Mary Monastery at Zeytinliada, Erdek) close to the Imperial capital of Constantinople (present-day Istanbul), which may have attracted a more diverse set of foreigners.
Other outliers are found at the periphery of the Southern Arc in the Iron Age, in Moldova and Romania, long after the early steppe migrants previously discussed. These are distinctive because of the East Eurasian admixture of Central Asian Scythian individuals (31–33).
