Greater Finland was a nationalist idea which emphasized territorial expansion of Finland according to the territorial boundaries encompassing nations who spoke Finnish or languages related to Finnish. The most coined version of Greater Finland was thought to be limited by natural borders encompassing the territories inhabited by Finns and Karelians.
The Greater Finland idea gained dramatically in popularity and influence after Finland gained independence in 1917. In connection with the October Revolution and civil war in Russia the situation in the Finnic inhabited areas adjacent to Finland's eastern border was considered unstable and exploitable by nationalists. For example, some Finnish volunteer troops carried out operations across the border into Russian territory. These activities, along with the participation of Finnish volunteer troops in the Estonian war of independence (1918-1920) are known in Finland's history as heimosodat ("kindred peoples wars," in the sense of wars related to the Finnish kinship).
In utopian mind-sets the most extended Greater Finland included the entire area colored in blue shades in the map. The light blue shows the are of Finland after gaining independence from Russia in 1917. In the Continuation war the Finnish troops went across this “old border” in the east, which has been considered as a sign of Greater Finland ideology among Finland’s political and military decision makers. The ideology lost its ground and support after the Continuation war.