The Tornio River (Finnish: Torniojoki; Swedish: Torneälv) is the modern border between the Republic of Finland and the Kingdom of Sweden. Prior to 1809, it was not a national border at all since Finland was then the eastern part of the Swedish Crown territories.
Along the Tornio Valley (Finnish: Tornionlaakso; Swedish: Tornedalen) from centuries past, there has been a common Finnish culture that included the area west of the river in modern-day Sweden and the area east of the river in modern-day Finland. This common culture has become known by the Swedish name Tornedalen (also Tornedalian) and has its own dialectic form of the Finnish language called meänkieli, from the Finnish meidän kieli [meidän > dialectic form meijän > meän], meaning 'our language.'
So the Tornedalens born and raised in the valley along both sides of the river were predominantly mainly ethnic Finns, most with very Finnish names and ancestries. Even some of them with very Swedish surnames — like 'Julin' and 'Westerberg' and 'Gertström' — were actually Finnish.
Tornedalians Genealogy on Facebook - est. Jan 2009 by Vivian Gullickson White
Tornedalian EmigrantMUSeum (EMUS)
<more links to come>