Dacia, a province of the Roman empire, bounded N. by the Carpathian mountains, which separated it from Sarmatia, S. by the Danube (Ister, Danubius), which separated it from Mcesia, E. by the Pruth (Hierasus) and the Euxine, and W. by the Theiss (Tibiscus, Tysia). It comprised part of Hungary, Transylvania, and Roumania. According to some, it included N. E. the Bukowina, and E. Bessarabia. Before the Roman conquest it was the habitation of the Daci, probably of Thra-cian origin, called by historians the most warlike of men, and according to some identical with the Getae, who at the time of Darius's Scythian expedition lived between the Balkan and the Danube. Strabo speaks of the Getse as living in the E. and the Daci in the W. part of the country. In the reign of Augustus they crossed the Danube, plundered the allies of the Romans, and spread terror even among the latter, but were finally driven back. Under their king Decebalus they compelled Do-rnitian, after a protracted struggle, to purchase peace by an annual tribute. The emperor, however, decorated himself with the title of Dacicus. Trajan refused to pay the tribute, and renewed the war. Decebalus ended the struggle only with his life (A. D. 106), after exhausting every resource of valor and policy.

The new province was colonized by inhabitants from all parts of the empire, with whom originated the Romanic language of the modern Wallachs, both in Transylvania and Roumania. Notwithstanding the resolution of the successors of Trajan to contract the limits of the empire, Dacia remained one of its provinces. In the 3d century it was invaded by the Goths, and resigned to them by the emperor Aurelian, who removed the Roman inhabitants to Moesia, giving the name of Dacia to that part of it in which they settled.