The name of the town sounded different in the languages spoken by its population. Thracians and Greeks pronounced it as Messambria. Strabo, the Greek geographer, wrote: "Next comes Messambria, a Megara colony, earlier called Melsambria, i.e., 'the town of Melsas', because its founder was called Melsas, and the Thracian word for 'town' was "bria". The Romans and Bysantines called the town 'Messembria' but they did not forget its Thracian founder. The epitaph of Roman Julia read: " ...My homeland is Messambria, of Melsa and bria...". In the Middle Ages the Bulgarian inhabitants called the town "Nessebur".

A large number of stone anchors dated to 12th century BC and demonstrating energetic seafaring in those early times were found in the aquatory of the two town ports. The greyish black pottery with decorations engraved and embossed, and dated to 9th - 6th century BC, make up the greatest part of the everyday life remains left by Ancient Thracians.

A most important inscription - decree in honour of Thracian leader Sadala, dated to 3th century BC, was found in Messambria. This monument supplied rich information concerning the relations between the Greek polis and neighbouring Thracians. The silver coin treasure (tetradrachmae) exhibited, where the Thracian imitations of Tassos tetradrachmae are prevalent, too, added to the knowledge of the role played by the local Thracian population in the political and economic life of the town between 11th - 1st century BC.