1748
"A Chart of the Baltic Sea, Gulfs of Finland and Bothnia, with the Sound, Drawn from the Best Maps & Charts by T. Jefferys, Geographer to His Royal Highness the Prince of Wales"

The Baltic Sea was known as the Mare Suebicum or Mare Sarmaticum at the time of the Roman Empire.

Since the Viking age, the Scandinavians have called it "the Eastern Lake", but Saxo Grammaticus recorded in Gesta Danorum an older name Gandvik, "-vik" being Old Norse for "bay", which implies that the Vikings correctly regarded it as an inlet of the sea.

In the early Middle Ages, Vikings of Scandinavia fought for power over the sea with Slavic Pomeranians. The Vikings used the rivers of Russia for trade routes, finding their way eventually all the way to Black Sea and southern Russia.

Finland and the Baltic states were the last in Europe to be converted into Christianity in the Northern Crusades: the former in the 12th century by the Swedes and the latter in the 13th century by the Germans. First the Livonian Brothers of the Sword and then the powerful German Teutonic Knights held the Baltic countries and fought with Danes and the Swedes, while the foundations of Russia were being laid in Novgorod.

Later on, the strongest economic force in Northern Europe became the Hanseatic league, which used the Baltic Sea to establish trade routes between its member cities. In the 16th and early 17th centuries, Poland, Denmark and Sweden fought wars for Dominium Maris Baltici (Ruling over the Baltic Sea). Eventually, it was the Swedish empire that virtually encompassed the Baltic Sea. In Sweden the sea was then referred to as Mare Nostrum Balticum (Our Baltic Sea). In the 18th century Russia and Prussia became the leading powers over the sea.