Does the territory of the Russian Empire include Finland? How did Finland become independent?

Yes. Finland fell first to Sweden and then to the Russian Empire.

In the 12th and 13th centuries, a large number of Swedes immigrated to the south and northwest coast of Finland. In the ?land Islands and the archipelago between ?land and Turku, Swedish was even more common than today. Swedish also became the language of the upper classes in other parts of Finland.

The episcopal diocese of Turku was established in the 13th century. Turku Cathedral is the center of worship for Saint Henry and the cultural center of the region. Bishops at that time had greater religious authority than today and were often the most powerful people in the area. The bishop was usually a Finn, but the commanders of the castle were usually Swedish or German nobles. In 1362, Finnish representatives were invited to participate in the election of the King of Sweden. This event is often seen as a manifestation of Finland's integration into the Kingdom of Sweden.

In the Finnish War of 1808, Sweden lost the war with Russia, and Finland was occupied by the troops of Russian Tsar Alexander I. After that, Finland broke away from Sweden and became an autonomous Grand Duchy within the Russian Empire, with the Tsar also serving as Grand Duke until 1917.

Shortly after the Bolshevik Revolution in Russia (October Revolution) on December 6, 1917, Finland declared its independence.