The Element Encyclopedia of Witchcraft: The Complete A-Z for the Entire Magical World - Judika Illes 2005
Bereginy refers to a host of Slavic water spirits in the retinue of a primal goddess named Bereginia (also Berehinia, Perehinia). Bereginy is Russian; the Polish variant is Bóginki.
Bereginia means “earth” and “shore,” and so perhaps indicates the threshold where land and water meet. River, forest, and lake spirits, the Bereginy are often depicted in the guise of double-tailed mermaids. Some believe these primeval Slavic spirits are the ancient ancestors of the Rusalka and Vila (see pages 439 and 443); others suggest that they are sister spirits, with the Bereginy inhabiting banks overlooking the waters where the Rusalka dwell.
The first recorded historical reference to Bereginia is from a sixth-century Greek lexicon naming gods and goddesses who were taboo for Christians. Among the spirits listed to avoid is “the Berehinia.”
The Bereginy, however, remained publicly honored by Slavic women as late as the Middle Ages, with secret devotions continuing long after. Christian chroniclers complained that the Bereginy were dangerous spirits because of the persistence with which women continued to serve them secretly. Rituals once held openly on the banks of rivers would eventually be held in sacred, secret, private places like the bathhouse. (See PLACES: Bathhouse.)