The term in Finnish historiography heimosodat (German: Kriege verwandter Völker) has been translated literally into English as "Kindred Nations Wars", "Wars for kindred peoples" or "Kinship Wars," specifically Finnic kinship. It is sometimes erroneously translated as "Tribal Wars". It refers to conflicts in territories inhabited by other Finnic peoples, often in Russia or in borders of Russia. Finnish volunteers took part in these conflicts either to assert Finnish control over the areas inhabited by related Finnic peoples or to help them to gain their independence. Many of the volunteer soldiers were inspired by the idea of Greater Finland. Some of the conflicts were incursions from Finland and some were local uprisings, where volunteers wanted either to help the people in their fight for independence or to annex the areas to Finland. According to Roselius, about 10,000 volunteers from Finland took part in the armed conflicts mentioned below.
- Estonian War of Independence (1918–1920)
- Viena expedition (1918)
- Aunus expedition (1919)
- Petsamo expeditions (1918 and 1920)
- East Karelian Uprising (1921–1922)
- National revolt of Ingrian Finns (1918–1920)
The phenomenon is closely linked to nationalism and irredentism, as Finland had just won its national independence, and a part of the population felt that they had obligations to help other Finnic peoples to attain the same. Estonia, the closest and numerically largest "kindred nation", had gained its independence at the same time, but had fewer resources, fewer institutions ready to support its attained position, and more Russian troops within its borders. Other Finnic peoples were at a less organized level of cultural, economic and political capability. The Finnish Civil War had awakened strong nationalistic feelings in Finnish citizens and other Finnic peoples, and they sought tangible ways to put these feelings into action. For the two next decades, Finns participated at a relatively high rate in nationalistic activities (e.g. Karelianism and Finnicization of the country and its institutions). This development was related to the trauma and divisiveness of the Civil War. Many White sympathizers in the Civil War became radically nationalistic as a result of the war. The strenuous five-year period 1939–45 of total war—which also mostly unified the nation—reduced this enthusiasm.
- "War", in this context, a low-intensity one, consisting of actions such as border skirmishes, expeditions by volunteer corps, expulsion of remnant occupational forces or attempts to foment rebellion in the local populace.
- "Tribe" or "clan", but in this context, also the ethnic and language kinship between Finnic peoples; "kindred peoples". Somewhat comparable to the German concept of Völkisch.
- People who are linguistically and/or ethnically akin to one another; "suku" means "family" and "kansa" means "people" (singular).
- Zägel, Jörg; Reiner Steinweg (2007). Vergangenheitsdiskurse in der Ostseeregion (in German). LIT Verlag Berlin-Hamburg-Münster. ISBN 978-3-8258-0202-8.
- Roselius, Aapo (2014). Finnish Irredentist Campaigns in the Aftermath of the Civil War // The Finnish Civil War 1918. History, Memory, Legacy. The Netherlands: Brill. p. 119. ISBN 978-90-04-24366-8.