Starting around 1200 BC, the western coast of Anatolia was heavily settled by Aeolian and Ionian Greeks. Numerous important cities were founded by these colonists, such as Miletus, Ephesus, Smyrna and Byzantium, the latter founded by Greek colonists from Megara in 657 BC. All of Thrace, and the native Thracian peoples were conquered by Darius the Great in the late 6th century BC, and were re-subjugated into the empire in 492 BC following Mardonius' campaign during the First Persian invasion of Greece. The territory of Thrace later became unified by the Odrysian kingdom, founded by Teres I, probably after the Persian defeat in Greece.