Scandinavia ( ) is a subregion in Northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. In English usage, Scandinavia most commonly refers to Denmark, Norway, and Sweden. It can sometimes also refer more narrowly to the Scandinavian Peninsula (which excludes Denmark but includes part of Finland), or more broadly to include all of Finland, Iceland, and the Faroe Islands. The geography of the region is varied, from the Norwegian fjords in the west and Scandinavian mountains covering parts of Norway and Sweden, to the low and flat areas of Denmark in the south, as well as archipelagos and lakes in the east. Most of the population in the region live in the more temperate southern regions, with the northern parts having long, cold, winters. The region became notable during the Viking Age, when Scandinavian peoples participated in large-scale raiding, conquest, colonization and trading mostly throughout Europe. They also used their longships for exploration, becoming the first Europeans to reach North America. These exploits saw the establishment of the North Sea Empire which comprised large parts of Scandinavia and Great Britain, though it was relatively short-lived. Scandinavia was eventually Christianized, and the coming centuries saw various unions of Scandinavian nations, most notably the Kalmar Union of Denmark, Norway and Sweden, which lasted for over 100 years until the Swedish king Gustav I led Sweden to independence. It also saw numerous wars between the nations, which shaped the modern borders. The most recent union was the union between Sweden and Norway, which ended in 1905. In modern times the region has prospered, with the economies of the countries being amongst the strongest in Europe. Sweden, Denmark, Norway and Finland all maintain welfare systems considered to be generous, with the economic and social policies of the countries being dubbed the "Nordic model". Geography The geography of Scandinavia is extremely varied. Notable are the Norwegian fjords, the Scandinavian Mountains covering much of Norway and parts of Sweden, the flat, low areas in Denmark and the archipelagos of Finland, Norway and Sweden. Finland and Sweden have many lakes and moraines, legacies of the ice age, which ended about ten millennia ago. The southern regions of Scandinavia, which are also the most populous regions, have a temperate climate. Scandinavia extends north of the Arctic Circle, but has relatively mild weather for its latitude due to the Gulf Stream. Many of the