The established view was that these earliest known inhabitants of Finland had arrived mostly by land from eastern Europe.
This sounds like the Finns arrived much like the Slavs did, to claim the north for themselves, which is not accurate.
Finland is full of archeological evidence that Baltic Finns/Karelians have lived there for thousands of years, fishing and hunting as usual.
Many of these immigrants were actually Central European Finno-Ugrians who spoke a related language, but whose language was eventually buried under several layers of Germanic languages.
Finnish tribes followed the ice north over thousands of years from their interglacial central European home, which is now established in the latest Mitochondrial DNA information.
New evidence suggests that Finno-Ugric peoples' range was much greater southward than previously thought.