The Bastarnae were a Celtic Balkan tribe which inhabited the region between the Carpathian mountains and the Dnieper River from 200 BC to 300 AD. The Bastarnae were originally a Celtic tribe which originated in the lower Vistula River valley, but, in 200 BC, the Celts and some Germans migrated southeast to the North Pontic region, and some of them were assimilated into the Sarmatians by the 3rd century AD. During the 1st century BC, the Bastarnae, Sarmatians, and Dacians unsuccessfully resisted Roman expansion into Moesia and Pannonia, and they maintained friendly relations with the Roman Empire during the first two centuries AD. In 180 AD, they participated in an invasion of Roman territory, and, in the mid-3rd century AD, they took part in a Gothic-led coalition which repeatedly invaded the Balkan provinces of the Roman Empire. Large numbers of the Bastarnae were resettled within the empire in the late 3rd century AD.