Not much is known about Finland's early history, with archaeologists still debating when and where a tribe of Finno-Ugric speakers cropped up. Roman historian Tacitus mentions a tribe primitive and savage Fenni in 100 AD, even the Vikings chose not to settle, trading and plundering along the coasts.
In the mid-1150s Sweden started out to conquer and Christianize the Finnish pagans in earnest, with Birger Jarl incorporating most of the country into Sweden in 1249. Finland stayed an integral part of Sweden until the 19th century, although there was near-constant warfare with Russia on the eastern border and two brief occupations. After Sweden's final disastrous defeat in the Finnish War of 1808-1809, Finland became an autonomous grand duchy under Russian rule after 1809.
Russian rule alternated between tolerance and repression, and there was already a significant independence movement when Russia plunged into war and revolutionary chaos in 1917. Parliament seized the chance and declared independence in December, quickly gaining Soviet assent, but the country promptly plunged into a brief but bitter civil war between the conservative Whites and the Socialist Reds, eventually won by the Whites.
During World War II, Finland was attacked by the Soviet Union in the Winter War , but fought them to a standstill that saw the USSR conquer 12% of Finnish territory. Finland then allied with Germany in an unsuccessful attempt to repel the Soviets and regain the lost territory, was defeated and, as a condition for peace, had to turn against Germany instead. Thus Finland fought three separate wars during World War II. In the end, Finland lost much of Karelia and Finland's second city Vyborg, but Soviets paid a heavy price for them with over 300,000 dead.
After the war, Finland fell into the Soviet sphere of influence and toed the Russian line on foreign policy, but maintained a studied policy of official neutrality and managed to retain a free market economy and multi-party elections, building close ties with its Nordic neighbors. This balancing act of Finlandization was humorously defined as "the art of bowing to the East without mooning the West". While there were some tense moments, Finland pulled it off: in the subsequent half century, the country made a remarkable transformation from a farm/forest economy to a diversified modern industrial economy featuring high-tech giants like Nokia, and per capita income is now on par with Western European countries.
After the implosion of the USSR, Finland joined the European Union in 1995, and was the only Nordic state to join the euro system at its initiation in January 1999.