Achaia, sometimes spelled Achaea, was a province of the Roman Empire, consisting of the Peloponnese, Attica, Boeotia, Euboea, the Cyclades and parts of Phthiotis, Aetolia and Phocis. In the north, it bordered on the provinces of Epirus vetus and Macedonia. The region was annexed by the Roman Republic in 146 BC following the sack of Corinth by the Roman general Lucius Mummius, who was awarded the surname "Achaicus". Initially part of the Roman province of Macedonia, it was made into a separate province by Augustus.

The province of Epirus was a province of the Roman Empire, covering the region of Ancient Epirus. Rome first annexed the region in 167 BC, in the aftermath of the Third Macedonian War, and initially put the region in the larger Roman province of Macedonia, which at the time covered the whole of the Hellenistic world in mainland Europe. In 27 BC, Epirus and Achaea were separated from Macedonia and grouped into the senatorial province of Achaea, with the exception of its northernmost part, which remained part of the province of Macedonia. Under Emperor Trajan, sometime between 103 and 114 AD, Epirus became a separate province, under a procurator Augusti. The new province extended from the Gulf of Aulon (Vlorë) and the Acroceraunian Mountains in the north to the lower course of the Acheloos River in the south, and included the northern Ionian Islands of Corfu, Lefkada, Ithaca, Cephallonia, and Zakynthos.