The province of Achaia derived its name from the region which the Achaean people, also known as the Greeks, inhabited in ancient times (Homer, Iliad). In pre-Roman times, the area had a common culture and language, but was politically divided into many independent city-states that occasionally allied with each other when it was mutually beneficial, such as when the Persians invaded Greece (Herodotus, Histories). In about 280 BC, the city-states of this area formed a confederation called the Achaean League, which functioned until their defeat by the Romans at Corinth in 146 BC, after which the area became part of the Roman province of Macedonia. In 27 BC, Augustus detached Achaia from Macedonia and transformed it into its own province, using the traditional name but applying it to a larger area which included everything south of a line from the Eubian Gulf to Actium. This province of Achaia encompassed what is today the southern part of modern Greece, including the major cities of Athens and Corinth. The New Testament usage of Achaia seems to always refer to the Roman province rather than the more ancient, smaller region from which the name was derived (Acts 18:27, 19:21; Romans 15:26; 2 Corinthians 1:1, 9:2; 1 Thessalonians 1:7-8). During the Roman period, Corinth was the largest city of the province and the capital, where the governor was stationed, but Athens remained an important center of learning (Acts 18:12). Cenchreae was an important port city east of Corinth, and Delphi, with the temple of Apollo and the Oracle, had been a primary religious center, but had lost much of its influence in the Roman period. Paul spent time in both Athens and Corinth, and wrote two letters to the church at Corinth, which was also intended for all of the Christians in the rest of the province (Acts 17:22, 18:1; 2 Corinthians 1:1). In 44 AD during the reign of Claudius, the province had been transformed back into a senatorial province once again governed by a proconsul, who lived at Corinth (Hemer, Acts; Acts 18:12; from 15-44 AD it was ruled by a legate who reported to the Emperor). Industries and exports included marble, mining, olives, pottery, furniture, education, and doctors and teachers. It was one of the most sought after provinces for Roman governors, as it was both peaceful and prosperous, and as a senatorial province it had limited interference from the Emperor. The famous historian Plutarch, who lived in the 1st and 2nd centuries AD and wrote Lives of the Emperors, lived in Achaia Province. Achaia was one of four provinces in the Roman Empire that Paul focused on, in addition to Asia, Galatia, and Macedonia, although he also visited and taught in many others on his missionary journeys.