Another fundamental traditional teaching, which I have discussed elsewhere with corresponding documentation, is the location of the center or primordial seat of the Olympian civilization of the Golden Age in a Boreal or Nordic-Boreal region that became uninhabitable. A tradition of Hyperborean origins, in its original Olympian form or civilizing deeds performed by races that spread into the Eurasian continent during the period from the end of the glacial age through the Neolithic Era. Some of these races must have come directly from the North; others seem to have had as their country of origin a Western-Atlantic land in which some kind of replica of the Northern center had been established. This is the reason why various concordant symbols and memories refer to a land that sometimes is Northern-Arctic and other times Western.
Among the many designations of the Hyperborean center that came to be applied also to the Atlantic center was Thule, or “White Island”, or “Island of Splendor” (the Hindu Sveta-dvipa; the Hellenic Leuke island; the “original seed of the Arian race” or Ariyana Vaego in ancient Iran); and “Land of the Sun”, or “Land of Apollo”, that is, Avalon. Concordant memories in all Indo-European traditions talk about the disappearance of such a seat (which later on was mythologized) following an ice age or a flood. This is the real, historical counterpart of the various allusions to something that, beginning with a given period, has allegedly been lost or become hidden and untraceable. This too is the reason why the “Island” or “Land of the Living” (the term “living” here referring to the members of the original divine race), which is the land to which the well-known symbols of the Supreme Center of the world allude, was often confused with the “region of the dead” (the term “dead” here referring to the extinct race). Thus, for instance, according to a Celtic doctrine, mankind’s primordial ancestor was the god of the dead (Dispater) who dwells in a faraway region beyond the ocean, in those “faraway islands” whence, according to the Druids’ teachings, some of the prehistoric inhabitants of Gaul came directly. Moreover, according to a classical tradition, after having been the lord of this earth, the king of the Golden Age, Kronos-Saturn, was dethroned and castrated (that is, deprived of the power to beget, to give life to a new stock); he still lives, though asleep, in a region located in the Far North, close to the Arctic sea, which was also called the Cronid Sea.
This generated various conditions, but essentially it is always the same transposition in superhistory, under the species of a latent or invisible reality or center, of ideas referring to the Hyperborean theme. For my purposes, I will need to discuss briefly the form that these memories assumed in the Celtic and especially in the Irish cycle; the traditions concerning Avalon, the Tuatha de Danaan, and the kingdom of Arthur. The scope of these traditions is more than local and historical; often, even the geographical data appearing in them have a merely symbolic meaning, as is often the case in these instances.
 Revolt Against The Modern World, Chapters 24-26.
 Especially in the tradition referred to by Diodorus Siculus (Bibliotheca Historica II, 47), the…White Island, is identified with the land of the Hyperboreans; it was situated in the ocean, before the land of the Celts; it is also indicated as Apollo’s island.
 The Irish name “Land Beneath the Waves” (Tir fa Tonn), applied to an image of this region, incorporates a memory of its sinking and submersion.
 Here it is the land of Thule, which, according to Strabo (ca. 63 B.C.E. — after 21 C.E.) was located at six days of navigation from the coast of Britannia, close to the frozen sea. In regard to the heroes of the primordial age, there is an interesting tradition according to which Kronos, already king of that age, often appears as king of heroes (Hesiod, Opera et dies, 168-71).
Excerpt from Julius Evola, The Mystery of the Grail: Initiation and Magic in the Quest for the Spirit, from http://www.galacticapublishing.com/HyperboreanTheme.htm.