Sampo comes from legendary times, supposedly forged by the smith Ilmarinen in exchange for his wife’s hand in marriage. It is said to be one of the Five Keys which, when combined, can restore Kela the Guardian to her corporeal form.
Sampo was last possessed by the demigod/sorcerer, Louhi, before her ship was sunk 100 kilometers northeast of Kotime by the demigod/sea demon, Iku-Turso. Few scholars agree on what Sampo looks like or what its purpose was, but the most common explanation is that it was a huge, magical millstone. Other legends say that it was a menhir or obelisk that served as a world tree or the channeling point of a ley line nexus.