The Bastarnae (Latin variants: Bastarni, or Basternae; Ancient Greek: Βαστάρναι or Βαστέρναι) and Peucini (Ancient Greek: Πευκῖνοι) were two ancient peoples who between 200 BC and 300 AD inhabited areas north of the Roman frontier on the Lower Danube. The Bastarnae lived in the region between the Carpathian Mountains and the river Dnieper, to the north and east of ancient Dacia. The Peucini occupied the region north of the Danube Delta.
The earliest Graeco-Roman historians to refer to the Bastarnae imply that they spoke Celtic languages. In contrast, later historical sources imply that they spoke Germanic languages, and could be considered Germanic peoples. Like other peoples who lived in the same geographical region, Graeco-Roman writers also referred to the Bastarnae as a Scythian people, but this was a general term, not a linguistic category.
Although largely sedentary, some elements may have adopted a semi-nomadic lifestyle. So far, no archaeological sites have been conclusively attributed to the Bastarnae. The archaeological horizons most often associated by scholars with the Bastarnae are the Zarubintsy and Poienesti-Lukashevka cultures.
The Bastarnae first came into conflict with the Romans during the 1st century BC when, in alliance with Dacians and Sarmatians, they unsuccessfully resisted Roman expansion into Moesia and Pannonia. Later, they appear to have maintained friendly relations with the Roman Empire during the first two centuries AD. This changed c. 180, when the Bastarnae are recorded as participants in an invasion of Roman territory, once again in alliance with Sarmatian and Dacian elements. In the mid-3rd century, the Bastarnae were part of a Gothic-led grand coalition of lower Danube tribes that repeatedly invaded the Balkan provinces of the Roman Empire.
Many Bastarnae were resettled within the Roman Empire in the late 3rd century.