A 19th-century fairy tale, not a pagan myth
This tale was collected by Alexander Afanasyev and published as part of Narodnye russkie skazki (1855–1863), the great 19th-century compendium of East Slavic oral folklore. It has no pagan-era attestation and is presented here as folklore, not as ancient religion, though it is among the best-loved and most widely translated Russian fairy tales.