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A Swedish independent state emerged during the 12th and 13th Century. After the Black Death in the middle of the 14th Century, which hit Scandinavia just as hard as in most other parts of Europe, killing about a third of the population, the Hanseatic League threatened the whole of Scandinavia's culture, finances and languages. This led to the forming of the Scandinavian Kalmar Union in the end of the 14th Century. But with the union followed other problems and in the 1520s Sweden left this union. With the Swedish involvement in the Thirty Years War, on the Reformist side, began an expansion of its territories. And the Swedish Empire was formed. This became one of the great powers of Europe until the early 18th century. Swedish territories outside the Scandinavian Peninsula were gradually lost during the 18th and 19th centuries, ending with the annexation of present-day Finland by Russia in 1809. The last war in which Sweden was directly involved was in 1814, when Norway was militarily forced into personal union. Since then, Sweden has been at peace, maintaining an official policy of neutrality in foreign affairs. The union with Norway was peacefully dissolved in 1905, leading to Sweden's current borders. Though Sweden was formally neutral through both world wars, Sweden engaged in humanitarian efforts, such as taking in refugees from German-occupied Europe.