The Bastarnae or Basternae are an ancient tribal group of probably Germanic, and Celtic origin which, between not later than 200 BCE and until at least CE 300, inhabits the region between the eastern Carpathian mountains and the Dnieper river (corresponding to the modern Republic of Moldova and western part of southern Ukraine).

A branch of the Bastarnae, called the Peucini by Greco-Roman writers, occupied the region north of the Danube river delta.Although possibly Celtic-speaking in 179 BCE, the Bastarnae probably were Germanic in language and culture during the 1st century AD, but appear to have become assimilated by their neighboring Sarmatians by the 3rd century.

Like the latter, they were probably semi-nomadic.

It has not yet been possible to identify specific Bastarnae archaeological sites.The Peucini branch of the Bastarnae first came into conflict with the Romans in the 1st century BCE, when they resisted, ultimately unsuccessfully, Roman expansion into Moesia, the region on the southern bank of the Danube.

Although probably on friendly terms with the Romans in the early 1st century, there is little evidence of the Peucini until ca.

180, when they are recorded as participating in an invasion of Roman territory 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 which inflicted immense damage on the Balkan provinces of the Roman empire in a series of massive invasions.

Large numbers of Bastarnae were resettled within the empire in the late 3rd century.