History of Pomorie - Bulgarian Black Sea Coast
Possibly founded in the 5th or 4th century BC as a colony of Apollonia (today Sozopol), Anchialos was mentioned in Strabo's Geographica as a small town. It was briefly captured by Messembria (Nesebar) in the 2nd century BC, but reconquered by Apollonia and its fortified walls destroyed. The name Anchialos is derived from Ancient Greek "anchi-" ("near, close to") and "als-" (either "salt" or a poetic and uncommon word for "sea").
The western Black Sea coast was ultimately conquered by the Romans under Marcus Licinius Crassus in 29-28 BC after continuous campaigns in the area since 72-71.
The fortified wall was meanwhile rebuilt, as evidenced by Ovid in 9 AD en route to Tomis. In the early 1st century AD Anchialos was the centre of a strategia of the vassal Odrysian kingdom, and the town had a Thracian population in the 6th century AD according to the early Byzantine historian Procopius. As the Odrysian kingdom's self-independence was abolished in 45 AD, Anchialos became part of the Roman province of Thrace and was formally proclaimed a city under Emperor Trajan. At the time the city controlled a vast territory bordering that of Augusta Trajana (Stara Zagora) and reaching the Tundzha to the west, bordering that of Messembria to the north and the southern shore of Lake Burgas to the south. Anchialos acquired the appearance of a Roman city and thrived considerably in the 2nd and 3rd century under the Severan Dynasty, seving as the most important import and export station of Thrace.