Sweden, officially the Kingdom of Sweden, is a Scandinavian country in Northern Europe. Sweden borders Norway and Finland, and is connected to Denmark by a bridge-tunnel across the Øresund. Sweden's capital city is Stockholm, which is also the largest city. At 450,295 square kilometres, Sweden is the third-largest country in the European Union by area, with a total population of about 9.6 million. Sweden has a low population density of 21 inhabitants per square kilometre with the population mostly concentrated to the southern half of the country. About 85% of the population live in urban areas.For centuries, Sweden was inhabited by various Germanic tribes, who eventually became known as the Vikings. Sweden emerged as an independent and unified country during the Middle Ages. In the 17th century, the country expanded its territories to form the Swedish Empire. The empire grew to be one of the great powers of Europe in the 17th and early 18th centuries. Most of the conquered territories outside the Scandinavian Peninsula were lost during the 18th and 19th centuries. The eastern half of Sweden, present-day Finland, was lost to Russia in 1809. The last war in which Sweden was directly involved was in 1814, when Sweden by military means forced Norway into a personal union. Since then, Sweden has been at peace, remaining a largely neutral nation.Today, Sweden is a constitutional monarchy with a parliamentary democracy form of government and a highly developed economy. Sweden has the world's eighth-highest per capita income and ranks highly in numerous comparisons of national performance, including quality of life, health, education, protection of civil liberties, economic competitiveness, equality, prosperity and human development. Sweden has been a member of the European Union since 1 January 1995 and is a member of the OECD. It is also a member of the United Nations, the Council of Europe and the World Trade Organization.