Perun is strongly correlated with the near-identical Perkūnas/Pērkons from Baltic mythology, suggesting either a common derivative of the Proto-Indo European thunder god (whose original name has been reconstructed as Perkwunos), or that one of these cultures borrowed the deity from the other.
Artifacts, traditions and toponyms show the presence of the cult of Perun among all Slavic, Baltic and Ugro-Finnic peoples.