*Perkʷūnos is the reconstructed name of the Proto-Indo-European (PIE) Thunder God, and His name is cognate with the Proto-Baltic *Perkū́nas, from which we derive the Lithuanian Perkū́nas, the Latvian Pērkons and the Old Prussian Percunis. The Lithuanian theonym is thus the most conservative of the three Baltic god names. The Proto-Baltic theonym is likewise closely cognate with the Proto-Slavic *Perúnъ or to use its anglicised spelling, *Perun. From *Perun we derive the East Slavic Perun, attested in Russian, Ukrainian and Belarusian. The East Slavic forms preserve the stress and vowel quality closest to the Proto-Slavic. The earliest East Slavic attested form is Perunŭ, found in the Primary Chronicle, a primary source for the history of the East Slavs, compiled around the year 1110 in the Kiev area and covers the history of these people for the period 850 to 1110. The South Slavic theonym is also preserved as Perun (Serbian, Croatian, Bosnian, Slovene and Bulgarian). Among the West Slavs, Perun is preserved as the Czech form and Perún as the Slovak. Piorun is the Kashubian reflex, which is also the reflex for 'thunderbolt' in Polish. The Polish form is no longer a theonym but represents a crucial semantic shift to the 'thunderbolt' itself. So where the god's name disappeared it remains in the name of the thunderbolt in Polish. This shift of meaning from the god to His weapon is due to the effects of Christianisation among the Poles and a lack of written sources for pre-Christian religion among that people.
As my readers can see, the linguistic evidence for the Thunder God theonym and His PIE pedigree is very strong, and thus we can reconstruct the Balto-Slavic to be *Perkū́nas, the shared theonym of the Balts and Slavs. The PIE *Perkʷūnos is built from the following elements:-
. *per-/*perk-, 'to strike'.
. *pérkʷus, 'oak'.
. *-ū́nos, 'master of'/'one associated with'.
A reflex of the PIE/Proto-Balto-Slavic form can even be found in the Finnic Perkele, a borrowing from the Baltic as a loanword for the Thunder God which was later demonised by Christianisation and became associated with the 'Devil' and is used in modern Finnish as a profanity. This borrowing occurred due to the close proximity of the Finnic with the Baltic peoples. Perkele became an alternative name for the native Proto-Finnic Thunder God/Sky God, Ukko, which has the meaning of 'Old Man'. It should be emphasised here that Finnic is a Finno-Ugric, not an Indo-European language. While Perkele was used by the Finns, it was never used as theonym by the Estonians, who retained Uko as the name of their Thunder God/Sky God. The Estonians did not have the same cultural contact with the Lithuanians and Old Prussians as the Finns had.
There is also a high likelihood that the Old Norse Fjörgynn/Fjörgyn is a reflex of the same
*Perkʷūnos root. Fjörgynn is referred to as the father of Frigg in both of the Eddas, while Fjörgyn (Jörð) is said to be the mother of Thor. Fjörgyn stems from the Proto-Germanic *fergunja, meaning 'mountain'/'mountainous forest'. *fergunja in turn stems from the PIE *per‑kwun‑iyā, which has the meaning, 'the realm of *Perkʷūnos' ('the wooded mountains' or 'the mountain/earth goddess'), the suffix -iya being feminine. What we thus have here is a feminine counterpart of the Thunder God name. According to the theory of Hilda Ellis Davidson, Fjörgynn/Fjörgyn may be a fossilised remnant of a lost divine pair, along the lines of Nerthus/Njord (Religious Practices of the Northern Peoples in Scandinavian Tradition, 1990).
As an adjunct to my recent series of essays on the PIE Sky Father and Earth Mother, the Thunder God should be viewed as part of a tripartite system of:
. Sky/Thunder Father
. Earth Mother
. Thunder Son
*Perkʷūnos inherits his power from *Dyēus, the Sky Father, but He is born from or functionally tied to *Dʰéǵʰōm, the Earth Mother. He protects the fertility of the earth by releasing rain and defeating chaos. In many Indo-European traditions the Thunder God is the son of the Sky Father (Vedic, Baltic, Slavic, Germanic) and thus He may be viewed as the active agent of the Sky Father's power. However, it should be noted that the Thunder God's battles occur on the earth, not in the sky, and His sacred places are earthly features, such as oak trees and mountains. As son of the Earth Mother, He wields the power of the Sky Father, and is without a doubt the most powerful of the gods, the guardian of men, gods, the earth, cosmic order and the righter of wrongs. Not surprisingly, He is the most popular and loved of the gods, especially in the Baltic, Slavic and Germanic traditions,even to this very day.
Examples of Oak Trees and Groves Sacred to the Thunder God
. Zeus' Oak at Dodona.
. Donar's Oak at Geismar and Oldenburg, Germany.
. Thundersley from Old English Þunres lēah, a sacred grove in Essex, England.
. Thunderfield from Old English Þunres feld, a high chalk ridge used for assemblies near Horley, Surrey, England.
. Thunder Cross from Old English Þunres crosc, a pre-Christian way-marker at a hill-junction where three ridges meet in Kent, England. Later marked with a Christian cross.
. Thundersbarrow from Old English Þunres beorg (Thunor's barrow), a large hill-barrow on the South Downs in Sussex, England.
. Torslund (Thor's Grove), groves dedicated to Thor and dominated by oak trees, found in Zealand and Jutland, Denmark.
. Torskog, forests associated with Thor, often containing oaks, found in Funen and Jutland, Denmark.
. Torsager (Thor's Field/Thor's Acre), Djursland, Zealand, Denmark. A hilltop settlement dedicated to Thor and on which a church was later built.
. Torslunda (Thor's Grove) at Öland and Småland, Sweden.
. Torsåker (Thor's Field) at Ångermanland and Gästrikland, Sweden.
. Torsvi (Holy place/sacred enclosure of Thor) at Uppland, Sweden.
. Torshov (Thor's hof/Thor's enclosure) at Oslo and Trøndelag, Norway.
. Torsnes (Thor's Headland) at Sogn and Fjordane, Norway.
. Torsneset (Thor's Headland) at Østfold, Norway.
. Torsåsen (Thor's Ridge) at Vestfold, Norway.
. Torsgard (Thor's enclosed/sacred space) at Hallingdal, Norway.
. Perun's Oak at Novgorod, Russia.
. Perkunas' Oak at Nowa Wieś, Lithuania.
Examples of Bays, Waterfalls, Islands, Hills, Barrows and Mountains Sacred to the Thunder God
. Þórsmörk (Thor's Forest) in southern Iceland-a mountain-ringed valley.
. Torsbjerg (Thor's hill), an Iron Age sacred hill in Sønderjylland, Denmark, an area containing multiple hills, groves and ritual landscapes dedicated to Thor.
. Torshøj (Thor's Barrow/Thor's Hill) in Jutland, Funen and Zealand, Denmark.
. Torsbakke (Thor's Bank/Thor's Slope), a ridge overlooking the Roskilde Fjord, Denmark.
. Torsburgen in Gotland, Sweden.
. Torshalla / Torshälla (Thor's Rock/Slope/Hill), sacred place at the river crossing dedicated to Thor at Södermanland, Sweden.
. Torshaug (Thor's Barrow/Thor's Mound) at Trøndelag, Norway.
. Torsfoss (Thor's Waterfall) at Hardanger, Norway.
. Torsvik (Thor's Bay) at Hordaland, Norway.
. Torsøya (Thor's Island) at Møre and Romsdal, Norway.
. Torshella (Thor's Rock/Slope/Hill) at Østfold, Norway.
. Torshammar (Hammer-shaped crag) at Oslofjord region, Norway.
. Thunor's Hlaew, a burial mound in Suffolk, England.
. Thunor's Hill (from Old English Þunres hyll), Suffolk, England.
. Thundercliffe (from Old English Þunres clif- Thunor's Cliffe), a gritstone escarpment the Don Valley, Yorkshire, England.
. Tunworth from Old English Thunor-worth (Thunor's enclosure), a hilltop settlement on a high chalk hill in Hampshire, England.
. Donnersberg, near Kirchheimbolanden, Rheinland-Pfalz, Germany.
. Donnersberg, Erzgebirge Foothills, Sachsen, Germany.
. Donnerberg, Eifel mountains, Nordrhein-Westfalen, Germany.
. Donnerberg, Bayern, Germany.
. Thunerberg, Bayern, Germany.
. Donnerkupfe, Knüll Mountains, Hesse, Germany.
. Donnerskopf, Knüll Mountains, Hesse, Germany.
. Donnershübel, Thüringer Wald, Thüringen, Germany.
. Donnerkogel, Dachstein Alps, Upper Austria.
. Donnerwand, Styria/ Upper Austria border, Austria.
. Donnerstein, Tyrol, Austria.
. Donnergraben, Salzburg/Northern Limestone Alps, Austria.
. Donneralm, an Alpine pasture/high meadow, Styria, Austria.
. Donnerhöhe, Lower Austria, Austria.
. Thunberg, Canton Bern, Switzerland.
. Tunersee/Tuneralp, Bernese Oberland, Switzerland.
. Tonnerberg, Central Switzerland.
. Tonnerhütte, Central Switzerland.
. Donnerwetter‑Fluh, thunderstorm cliff in Switzerland.
. Perkūno's Hill in Perkūno Kalnas, Lithuania.
. Perkūno's Hill, near Kernavė, Lithuania.
. Perkūno's Hill, Jubarkas, Lithuania.
. Pirin, a mountain range in Bulgaria. Sacred to Perun.
. Velebit mountain range in Croatia. The key sacred peak being Sveto Brdo. Sacred to Perun.
This list of oak trees, groves, barrows, hills, bays, islands, waterfalls and mountains is not intended to be exhaustive, but illustrative of the importance of the Indo-European Thunder God and the survival of His name in our modern landscapes. It is my intention to begin work soon on what I envisage to be an exhaustive book on this very issue, but confined to the Germanic lands. I have set myself a goal of completing this work by my 70th birthday in just a few years time and it will be made available for purchase on completion. I intend the work to be part of my lasting legacy and it should prove to be of interest to both scholars and laymen. No such complete work yet exists in the English language on Thor toponyms collected together in a single volume.
