ACHAIA ə kā’ yə (̓Αχαία). The Rom. province which included all of the Peloponnesus, much of central Greece and the Cyclades.
The name is derived from ̓Αχαιοί, a common designation in Homer for the Greeks who besieged Troy in the 12th cent. b.c. It is generally applied to the followers of Agamemnon, who came from the fertile plains of Argos and the surrounding areas, and to the men of Achilles who came from Pithian Thessaly in the NE. It is also the name for the Greeks which is found in Hitt. and Egyp. texts of the period 1400-1200 b.c. That they were Gr.-speaking people is borne out by the decipherment of Linear B tablets from Late Bronze Age (Mycenaean) settlements at Mycenae, Pylos and Thebes. Herodotus (VII 94) was no doubt wrong when he stated that they supplanted the Ionians in the Peloponnesus after they moved from their original home in Thessaly. They were instead Gr.-speaking intruders who replaced the original inhabitants of both regions, prob. at the end of the Middle Bronze Age.
In historical times the name was applied to the N central part of the Peloponnesus. It extended from Elis to Sicyon and comprised the narrow, fertile plain and foothills between the Gulf of Corinth and the mountains behind. The twelve small towns located in this region formed a federal league which met first at Helice and later at Aegium. In the 3rd and 2nd centuries b.c. the league became the chief power of Greece. The league was remarkable as one of the most perfect examples of federal government. Every city had equal rights and managed its own internal affairs. In foreign affairs the federal government was supreme. It consisted of all citizens of all the towns and met twice a year to consider matters of common interest. The Achaean constitution was used as a model by the framers of the American Constitution.
After the conquest of Greece by the Romans in the middle of the 2nd cent., the league went into a sharp decline. The region was administered by the Rom. governor of Macedonia until the emperor Augustus in 27 b.c. divided Greece into two parts, Macedonia and Achaia. The latter became a senatorial province. Corinth, which had been rebuilt in 46 b.c., became the capital and the residence of the proconsul. Because of a dispute over taxes Tiberius in a.d. 15 reunited Achaia with Macedonia and Moesia under the administration of an imperial legate, but in 44 Claudius again made it a senatorial province. On the 28th of November 67 Nero declared Greece free at the Isthmian games, but Vespasian soon made it a senatorial province again.
During his first visit to Corinth Paul was dragged before the governor of Achaia, L. Junius Gallio Annaeus, by Jews who resented his teachings. The magistrate refused to become involved in their religious dispute nor did he interfere when the crowd beat Sosthenes, the ruler of the synagogue, in front of the judgment seat (Acts 18:12-17). The name Achaia is used in the NT to refer to the Rom. province or to its inhabitants (Acts 18:27; 19:21; Rom 15:26; 1 Cor 16:15; 2 Cor 1:1; 9:2; 11:10; 1 Thess 1:7f.).
Bibliography J. A. O. Larsen in T. Frank ed., Economic Survey of Ancient Rome vol. IV. 259-498; E. Groag, Die romischen Reichsbeamten von Achaia (1939); J. Toepffer and C. G. Brandis in Pauly Wissowa RE s.v., “Achaia.”