Well, Delfos, to make a long story short:
In the 14th through 18th century, Sweden Encompassed what now is Sweden, Finnland, parts of Estonia and to and fro also other parts of northern euroupe. During all this time, Sweden was fighting with it's traditional enemy: Tsar-Russia and in the last peace treaty with the Russians, Sweden was forced to part with Finnland which became Russian territory and Åland became a demilitarised zone.