The arrival of the Huns on the western steppe around 370 CE set off the chain of movements that historians call the Migration Period: the Alans were defeated and partly absorbed, the Goths were pushed onto the Danube and into the Roman empire, and further groups were driven west and south. Under Attila from the 440s the Huns extracted enormous tribute from Constantinople, destroyed Balkan cities including Naissus — which Priscus found still littered with bones years later — and campaigned into Gaul and Italy before Attila's death in 453 and the rapid collapse of his empire. Captives were a central object of Hunnic warfare: prisoners were incorporated into Hunnic forces and households, and treaties with Rome specified ransom rates and the surrender of fugitives. The Huns are included here because an organised steppe power displaced whole peoples and carried off populations, but no ancient source gives numbers, and the extent to which the Huns caused rather than accelerated the movements of the period is debated.
The Huns conquered and subordinated the peoples of the Pontic steppe and central Europe, driving Alans, Goths and others into and across the Roman frontier, and under Attila destroyed cities and carried off captives from the Balkans and Gaul
No denominator can be reconstructed. The groups involved — Alans, Greuthungi, Tervingi, Gepids, Sciri, Rugii and others — were mobile confederations with no registers, and the Roman sources that describe their movement give only rhetorical multitudes. Modern estimates for individual groups run to tens of thousands of people, but summing them across eighty years and a shifting set of peoples would be invention.
No range can be defended. Priscus and other contemporaries describe the destruction of Balkan cities and the killing of their inhabitants, and Priscus reports finding the ground at Naissus still covered with human bones, but no numbers were recorded and no archaeological estimate exists.
Priscus, who travelled to Attila's court, and other fifth-century writers record the sacking and depopulation of Balkan cities such as Naissus and the carrying off of their inhabitants.
Hungary, Russia, Romania, Bulgaria, Serbia