During various scenes in the series, you can hear themes from Finlandia, by the Finnish composer Jean Sibelius. It premiered in 1899, and immediately became a symbol against the recently started new wave of Russian oppression (Finland was a grand duchy of Russia 1809-1917). However, as the original Katri book is set in the middle of the 19th century, before the oppression, it might be better here to consider Finlandia as a symbol of Finland and Finnish spirit in a more general sense.