Norse mythology is the body of myths of the North Germanic peoples, stemming from Norse paganism and continuing after the Christianization of Scandinavia, and into the Scandinavian folklore of the modern period. The northernmost extension of Germanic mythology, Norse mythology consists of tales of various deities, beings, and heroes derived from numerous sources from both before and after the pagan period, including medieval manuscripts, archaeological representations, and folk tradition. Norse mythology is the body of myths of the North Germanic peoples, stemming from Norse paganism and continuing after the Christianization of Scandinavia, and into the Scandinavian folklore of the modern period. The northernmost extension of Germanic mythology, Norse mythology consists of tales of various deities, beings, and heroes derived from numerous sources from both before and after the pagan period, including medieval manuscripts, archaeological representations, and folk tradition. The source texts mention numerous gods, such as the hammer-wielding, humanity-protecting thunder-god Thor, who relentlessly fights his foes; the one-eyed, raven-flanked god Odin, who craftily pursues knowledge throughout the worlds and bestowed among humanity the runic alphabet; the beautiful, seiðr-working, feathered cloak-clad goddess Freya who rides to battle to choose among the slain; the vengeful, skiing goddess Skaði, who prefers the wolf howls of the winter mountains to the seashore; the powerful god Njörð, who may calm both sea and fire and grant wealth and land; the god Frey, whose weather and farming associations bring peace and pleasure to humanity; the goddess Iðunn, who keeps apples that grant eternal youthfulness; the mysterious god Heimdall, who is born of nine mothers, can hear grass grow, has gold teeth, and possesses a resounding horn; the jötunn Loki, who brings tragedy to the gods by engineering the death of the goddess Frigg's beautiful son Baldr; and numerous other deities. Most of the surviving mythology centres on the plights of the gods and their interaction with various other beings, such as humanity and the jötnar, beings who may be friends, lovers, foes or family members of the gods. The cosmos in Norse mythology consists of Nine Worlds that flank a central tree, Yggdrasil. Units of time and elements of the cosmology are personified as deities or beings. Various forms of a creation myth are recounted, where the world is created from the flesh of the primordial being Ymir, and the first two humans are Ask and Embla. These worlds are foretold to be reborn after the events of Ragnarök when an immense battle occurs between the gods and their enemies, and the world is enveloped in flames, only to be reborn anew. There the surviving gods will meet, and the land will be fertile and green, and two humans will repopulate the world. Norse mythology has been the subject of scholarly discourse since the 17th century, when key texts were brought to the attention of the intellectual circles of Europe. By way of comparative mythology and historical linguistics, scholars have identified elements of Germanic mythology reaching as far back as Proto-Indo-European mythology. During the modern period, the Romanticist Viking revival re-awoke an interest in the subject matter, and references to Norse mythology may now be found throughout modern popular culture. The myths have further been revived in a religious context among adherents of Germanic Neopaganism. The historical religion of the Norse people is commonly referred to as Norse mythology. In certain literature the terms Scandinavian mythology or Nordic mythology have been used. Norse mythology is primarily attested in dialects of Old Norse, a North Germanic language spoken by the Scandinavian people during the European Middle Ages and the ancestor of modern Scandinavian languages. The majority of these Old Norse texts were created in Iceland, where the oral tradition stemming from the pre-Christian inhabitants of the island was collected and recorded in manuscripts. This occurred primarily in the 13th century. These texts include the Prose Edda, composed in the 13th century by Snorri Sturluson, and the Poetic Edda, a collection of poems from earlier traditional material anonymously compiled in the 13th century. The Prose Edda was composed as a prose manual for producing skaldic poetry—traditional Old Norse poetry composed by skalds. Originally composed and transmitted orally, skaldic poetry utilizes alliterative verse, kennings, and various metrical forms. The Prose Edda presents numerous examples of works by various skalds from before and after the Christianization process and also frequently refers back to the poems found in the Poetic Edda. The Poetic Edda consists almost entirely of poems, with some prose narrative added, and this poetry—Eddic poetry—utilizes fewer kennings. In comparison to skaldic poetry, Eddic poetry is relatively unadorned. The Prose Edda features layers of euhemerization, a process in which deities and supernatural beings are presented as having been either actual, magic-wielding human beings who have been deified in time or beings demonized by way of Christian mythology. Texts such as Heimskringla, composed in the 13th century by Snorri and Gesta Danorum, composed in Latin by Saxo Grammaticus in Denmark in the 12th century, are the results of heavy amounts of euhemerization. Numerous further texts, such as the sagas, provide further information. The saga corpus consists of thousands of tales recorded in Old Norse ranging from Icelandic family histories (Sagas of Icelanders) to Migration period tales mentioning historic figures such as Attila the Hun (legendary sagas). Objects and monuments such as the Rök Runestone and the Kvinneby amulet feature runic inscriptions—texts written in the runic alphabet, the indigenous alphabet of the Germanic peoples—that mention figures and events from Norse mythology.