The Norse worshipped a family of gods who fought monsters, drank too much, lied, schemed, slept with each other's spouses, knew that they were doomed, and went into the final battle anyway because dying well was the point.

Norse mythology, as we know it, comes to us from two main sources. The Poetic Edda is a collection of about 30 anonymous mythological and heroic poems, composed in Iceland and Norway in the Viking Age and the centuries immediately following, preserved in a single 13th-century manuscript called the Codex Regius (Latin: "Royal Book"), which spent four hundred years in private hands until it was rediscovered in 1643 by an Icelandic bishop, presented to the Danish king, and survived World War II in a Copenhagen vault. The Prose Edda is a 13th-century systematic textbook of Norse mythology written by the Icelandic statesman, scholar, and saga-writer Snorri Sturluson (1179–1241) for the use of skalds (court poets) who needed to understand the old myths in order to compose properly even after the conversion. Snorri is our best single source on Norse cosmology. He was also a Christian writing 200 years after the official conversion, working from oral tradition and surviving poems, and his accounts have been smoothed and rationalized in places that we cannot always identify. Caveat: the Norse cosmology described below is the system as Snorri wrote it down, which is the closest we can get, but the actual Viking-era pagan religious experience was almost certainly more local, more variable, and less neatly structured than Snorri's textbook makes it look.

With that caveat, here is the system.

The cosmos contains nine worlds, arranged around or upon a vast world-tree called Yggdrasil (IG-druh-sil, "Odin's Steed," because Odin is said to have hung on the tree to gain wisdom — more on that in a moment). Yggdrasil is an enormous ash tree whose branches extend over all the worlds and whose roots reach down into the underworlds. It is sustained by the Well of Urd (the Well of Fate), where the Norns (three female fate-spinners, vaguely paralleling the Greek Fates and the Slavic Rozhanitsy, who carve the destinies of gods and men into the wood of the tree) tend its waters. The tree is gnawed by serpents at its roots, plagued by a dragon named Níðhöggr at its base, and crowned by an eagle who drops gossip to a squirrel named Ratatoskr, who runs up and down the trunk carrying insults between the eagle and the dragon. This is a cosmology with a sense of humor.

The nine worlds are arranged on three rough levels — gods above, humans in the middle, monsters and the dead below — and most of the action in the surviving myths happens by characters traveling between them. The names that matter most for the stories are these:

Asgard — the home of the Æsir (EYE-sir), the principal sky-gods (Odin, Thor, Tyr, and so on)
Midgard — Middle-Earth, the world of human beings (Tolkien borrowed the word and the concept directly)
Jotunheim — the home of the Jötnar (YERT-nar, often translated "giants" but really an older race of cosmological forces, often hostile, sometimes not, frequently the romantic partners of the gods)
Hel — the realm of the unhonored dead, ruled by a goddess named Hel, half a beautiful woman and half a corpse
Muspelheim — the world of fire, ruled by the fire-giant Surtr, who will burn the cosmos at Ragnarök

The other four — Vanaheim (an older lineage of fertility gods who fought and made peace with the Æsir), Niflheim (cold and mist), Alfheim (light-elves), and Svartalfheim (dark elves or dwarves) — fill out the system but rarely drive a story.

The principal gods of the Æsir:

Odin (in Old Norse Óðinn, OH-thin), the All-Father, god of war, wisdom, poetry, magic, and ritual ecstasy. Odin is one-eyed (he gave his other eye to drink at the Well of Mimir for wisdom). He hangs himself on Yggdrasil for nine days and nights, pierced by his own spear, in order to learn the secret of the runes. He has two ravens, Huginn ("Thought") and Muninn ("Memory"), who fly out across the world each day and return to whisper news in his ears. He has two wolves, Geri and Freki. He keeps a hall in Asgard called Valhalla ("Hall of the Slain"), where the slain warriors brought to him by the Valkyries (VAL-kuh-rees, "choosers of the slain" — armored female spirits riding through battle who select which warriors will die and join Odin) feast all night and fight all day in preparation for the final battle. Odin is the patron god of kings, of warriors, and of poets. He is also untrustworthy — he is the god most likely to break an oath, and the warriors who follow him know that he will eventually betray them, because he needs them dead and in Valhalla for his army at Ragnarök.

Thor (in Old Norse Þórr, THORE), the thunder god, son of Odin, the most popular deity in the Viking Age by a wide margin (Thor's-hammer pendants are by far the most common religious amulet in Norse archaeology, especially in the late pagan period when they appear as a deliberate counter-symbol to the Christian cross). Thor is a red-bearded, hot-tempered, immensely strong protector — of the gods, of humans, of the cosmic order against the giants. He drives a chariot pulled by two goats. He wields the hammer Mjölnir (MYERL-neer), which always returns to his hand after being thrown. Thursday is named for him.

Freyr (FRAYR) and his sister Freyja (FRAY-yah), the great Vanir gods of fertility, peace, and prosperity. Freyr controls rain and harvest. Freyja is associated with love, sexuality, gold, war (she gets half the slain; Odin gets the other half — a detail that gives a sense of her stature), and a magical art called seiðr (SAYTH, a kind of ritual divinatory magic that was generally considered women's work, and that was associated with shamanic practice; Odin himself could practice seiðr but it was considered effeminate for him to do so). Freyja drives a chariot pulled by two cats. Friday is named for her.

Tyr — the older war god, originally the principal sky-god of the proto-Germanic pantheon, demoted by the Viking Age to a supporting role behind Odin. He has only one hand, having sacrificed the other to bind the great wolf Fenrir.

Loki — not exactly a god, more of a trickster figure, the father of monsters (the wolf Fenrir, the world-serpent Jörmungandr, the goddess Hel). Loki is hilarious, treacherous, and ultimately catastrophic; he engineers the death of Odin's beloved son Baldur and is bound in a cave with a serpent dripping venom on his face until Ragnarök, when he will break free and fight against the gods.

And looming over the whole cosmology, the central feature that distinguishes Norse mythology from almost every other religious system in the world: Ragnarök (RAG-nar-erk, "Doom of the Gods" or "Twilight of the Gods").

The gods know that they are going to die. The Norns have foretold it. The whole cosmic order will end in a great battle at the end of time: the wolf Fenrir will break his chains and devour Odin; Thor will kill the world-serpent and walk nine paces and fall dead from its venom; the fire-giant Surtr will burn the world; the sun will be eaten; the stars will fall. After Ragnarök, a new world will rise from the sea, and a small remnant of gods and humans will repopulate it. But the present cosmic order — the gods we know, the heroes we know, the world we know — is doomed. The warriors in Valhalla are training for a battle they will lose. The heroism is in fighting anyway.

This is a religion of doomed nobility, and it shaped the Viking warrior ethic in concrete ways. A man fated to die cannot avoid his fate. The honorable thing is to face it well — to die with weapon in hand, with one's name on the lips of the next generation. (Whether the conventional Viking concept of Valhalla as "the warrior heaven" was as central to lived practice as the sagas suggest, or was sharpened in the post-conversion saga literature, is debated.) The poem Hávamál ("The Sayings of the High One"), the longest of the Eddic poems, contains lines that became proverbial: "Cattle die, kinsmen die, the self must also die; / I know one thing which never dies: / The reputation of each dead man." A reputation outlasts a body. Die well; live in your descendants' memory; that is what immortality is.

The lived practice of Norse paganism centered on blót (BLOTE) — sacrifice. A blót was a public ritual of animal slaughter (occasionally human, in extreme circumstances), conducted at major seasonal festivals to honor specific gods and seek their favor for the coming season. The slaughtered animal's blood was sprinkled on the altars, on the temple walls, and on the participants. The meat was cooked and eaten communally; the worshippers drank the blood (or, more commonly, an ale toasted in the names of the gods); and the rest of the carcass was burned. The chief blóts of the year:

Sigrblót (Victory-Blót) in early spring, dedicated to Odin, asking for victory in the coming raiding season
Miðsumarblót at midsummer, dedicated to Freyr, asking for a good harvest
Vetrnætrablót (Winter-Nights-Blót) in October, beginning the winter half of the year
Jólablót at midwinter (the origin of the word Yule, the great midwinter festival that Christianity would absorb and rebrand as Christmas)

The Dísablót was a midwinter sacrifice specifically for the dísir — collective female ancestral and fertility spirits. The Dísablót was particularly observed in Sweden, where the central royal cult site at Uppsala (uhp-SAH-la) hosted national-scale sacrifices into the late 11th century.

Adam of Bremen, a German cleric writing around 1075 (one of our key non-Norse sources for Viking-Age religion, though he is reporting at second hand from Saxon and Danish informants and is hostile to paganism), described the Great Heathen Temple at Uppsala in vivid and somewhat horrified detail: a wooden temple decorated with golden chains, containing three large wooden statues of Odin, Thor, and Freyr (Thor in the central position, with Odin and Freyr on either side); a sacred grove next to the temple where the bodies of sacrificial victims — humans, dogs, and horses — were hung from the trees; and a great festival every nine years at which 99 of each kind of victim (humans, dogs, horses, cattle) were sacrificed. Adam was repeating reports, and parts of his account — especially the human sacrifice details — may be exaggerated by his Christian informants. What is reasonably solid is that Uppsala was the central Swedish royal cult site, that animal sacrifice was a major part of Norse religious practice there, and that the temple persisted, against mounting Christian pressure, until the late 11th century. Uppsala was probably destroyed and replaced by a Christian cathedral around 1090.

The temple at Uppsala is the great late holdout of Norse paganism. By the time Adam was writing, every other major Scandinavian region had nominally converted. Sweden was the last domino, and its national royal cult held on for another century beyond the others.

The conversion of Scandinavia was not a single event. It was a 250-year process, full of false starts, reversions, forced baptisms, and political compromises. But the pivotal moments cluster in a roughly fifty-year window: the late 950s through the early 1000s, when most of the great Norse polities went officially Christian.

Denmark went first. Harald Bluetooth (Harald Blátǫnn, ruled c. 958–986) is the king who flipped Denmark, and he made sure everyone knew it. Harald was the son of Gorm the Old, the first historically attested king of a unified Denmark, and he was a politically capable, religiously pragmatic, and territorially ambitious ruler. Christianity had been seeping into Denmark for over a century, brought by Frankish missionaries (Ansgar in the 820s) and Christian merchants in the trading towns. By the 960s, Harald was under increasing pressure from the Holy Roman Empire (the German-led successor to Charlemagne's empire, then under Otto I) to convert his country, partly because Otto wanted to claim suzerainty over Denmark and a pagan kingdom was a legal target for crusade. Harald accepted baptism around 965 — the Saxon historian Widukind tells a vivid story about how a missionary named Poppo proved the Christian God's superiority by carrying a red-hot iron in his bare hand without injury, which convinced Harald, though the story is conventional and occurs in many medieval conversion narratives.

Harald commemorated his reign and Denmark's conversion with one of the most extraordinary monuments of the Viking Age: the Jelling Stones at the royal cult site of Jelling in central Jutland. Harald's father Gorm had erected an earlier, smaller runestone there for his queen Thyra. Harald topped his father's monument with a much larger one — a great runestone about ten feet (3 m) tall, on three faces of which is carved (in beautifully executed Viking-era runic script) the inscription:

"King Harald ordered these monuments made in memory of Gorm his father and Thyra his mother. That Harald who won for himself all of Denmark and Norway, and made the Danes Christian."

On one face is carved a writhing serpent-and-lion battle scene (a Viking animal style of high quality). On another face is carved one of the earliest depictions of Christ in Scandinavia — Christ outstretched against a tangle of vines, simultaneously crucified and triumphant. The Jelling Stone is, in effect, Denmark's baptismal certificate: a public state monument announcing the country's conversion, in the language of pagan runestones, with Christian imagery, planted in the old royal pagan cult site, by the king who unified the country. It is a propaganda masterpiece, and it works as a propaganda masterpiece a thousand years later: tourist buses still stop there.

Harald's son Sweyn Forkbeard (Sveinn Tjúguskegg) revolted against Harald around 986 and exiled him; Harald died of his wounds the same year. Sweyn was a more pragmatic Christian than his father and a more aggressive king. He would, two decades later, become the first Danish ruler of England.

Norway went next, less peacefully. Olaf Tryggvason (995–1000), a great-grandson of Harald Fairhair, returned from a youth of raiding in the Baltic and the British Isles and seized the Norwegian crown. Olaf had been baptized in England (probably in 994, following a major Viking raid that ended in a peace and a Christianization deal with the English king Æthelred) and he came home a fervent and violent convert. Over a five-year reign he campaigned across Norway forcibly Christianizing region after region — destroying pagan temples, killing recalcitrant chieftains, threatening farmers with mutilation if they refused baptism. He founded the city of Trondheim as a new Christian Norwegian capital. And he sponsored conversion missions to Iceland, Greenland, and the Faroes from his court. Olaf was a Christian crusader-king in the literal sense, and his campaigns were ferocious enough to leave a permanent mark on Norwegian historical memory. He died at the Battle of Svolder in 1000, betrayed and ambushed by a coalition of Danish, Swedish, and Norwegian rivals, leaping into the Baltic in his armor rather than be captured. His campaigns had succeeded in Christianizing the coastal regions; the inland Norwegian valleys would take another generation.

Olaf's successor as Christian crusader-king of Norway was his (probably distant) kinsman Olaf Haraldsson (1015–1028, later canonized as Saint Olaf). The second Olaf was a more systematic ruler and a more brutal Christianizer than the first — he sent missionaries (or warbands) into the inland valleys to destroy idols and force baptism, codified the first Norwegian Christian laws, and consolidated royal authority around the new church. He was overthrown by a coalition of Norwegian chieftains backed by Cnut the Great of Denmark in 1028, fled east into exile, returned with an army to reclaim his throne, and was killed at the Battle of Stiklestad on July 29, 1030.

Stiklestad was a tactical defeat that became a strategic victory. Within a year, miracles were being reported at Olaf's grave. Within a generation, he had been declared a saint — Norway's first and only national patron saint. The cult of Saint Olaf spread rapidly across Scandinavia, the Norse diaspora, and as far as the Anglo-Saxon and Russian churches; medieval pilgrim routes across Norway converged on his shrine at Nidaros Cathedral (NEE-dah-ros, the medieval name for Trondheim, where Olaf's body was eventually interred). The man who had fought to impose Christianity by force became, in death, the saint whose cult sealed the conversion he had tried to win in life. The mechanism is not unique — the same dynamic created the cult of Edmund the Martyr in England — but it is one of the cleanest examples of how a violent Christianization could eventually become a beloved national identity.

Iceland converted in 1000, and the Icelandic conversion is one of the most remarkable in religious history because it was accomplished by a single act of constitutional procedure.

By the 990s, Iceland was split between an increasingly large Christian minority (converts from voyages abroad, contacts with Norway, missionaries sent by Olaf Tryggvason) and a still-dominant pagan majority. The two factions were on the edge of civil war. Pagan and Christian Icelanders refused to honor each other's legal proceedings. Marriages were collapsing along religious lines. Olaf Tryggvason was holding Icelandic hostages at his court in Norway and threatening to refuse trade to a non-Christian Iceland.

In the summer of 1000, the Althing met at Þingvellir under enormous pressure. The Lawspeaker that year was Þorgeirr Ljósvetningagoði (THOR-gay-ir LYOSS-vet-nings-go-thee, "Thorgeir the Priest of the People of Light-Lake"), a respected pagan chieftain. Þorgeirr was asked, by both sides, to render a judgment that would prevent the country from breaking apart. He withdrew under his fur cloak, lay down on the grass, and refused to speak or move for a day and a night. (No one knows what he was doing under the cloak. The traditional Christian interpretation is that he was praying or meditating. The traditional pagan interpretation is that he was performing útiseta, "outside-sitting," a Norse divinatory practice in which a person sat outside in silent communion with spirits to receive guidance. Modern scholars cannot say which it was.)

When Þorgeirr emerged from the cloak, he announced his ruling: Iceland would adopt Christianity as its public religion. All Icelanders would be baptized. Public pagan worship would cease. But — and this was the brilliance — private pagan practice would be tolerated. People could still worship the old gods at home, eat horse meat (a pagan ritual food banned by the church), and expose unwanted infants (a pagan custom that the church banned in principle). The compromise gave the Christian faction the public victory it needed and gave the pagan faction time to convert organically.

Iceland was therefore Christianized by parliamentary vote in 1000, brokered by a pagan Lawspeaker, with pragmatic concessions on both sides, with no executions, no battles, and no martyrs. The Icelandic conversion is the cleanest, most procedural, and least violent religious transformation of the Viking Age. It is also, not coincidentally, the conversion that most thoroughly preserved the cultural memory of the pagan past — Iceland would, three centuries later, produce the Eddas and the sagas, the documents in which Norse mythology survives. The country that converted gently kept its old stories. The countries that converted by sword forgot more.

Sweden held out longest. The Swedish royal kingdom did not formally Christianize until the early 11th century under Olof Skötkonung (995–1022), the first Swedish king to be baptized (around 1008). But pagan practice persisted at the great central temple at Uppsala for another seventy years, into the 1080s, when the temple was finally destroyed and replaced by a Christian church. The Swedes are a useful reminder that the Viking-Age conversion was not a single switch. It was a long, regional, generation-by-generation process, and pockets of organized paganism survived until well after the conventional 1066 end-date of the Viking Age.

The conversion mattered in concrete ways beyond the religious. Christianity brought writing — the Latin alphabet replaced runes for serious documentation, kings began to issue charters and laws, monasteries became centers of literacy, and Iceland in particular took to the new technology with extraordinary energy. Christianity brought stone churches, which were built on top of old pagan cult sites in a pattern repeated all across Scandinavia (the present-day cathedrals of Lund, Trondheim, and Uppsala all sit on or next to old pagan sacred sites). Christianity brought diplomatic respectability: a Christian Norse king could marry a Christian Frankish princess, sign treaties with Christian kingdoms as a recognized political peer, and integrate his kingdom into the broader European political order. The conversion was, in part, a process of accreditation. To be Christian was to be admitted to the diplomatic club of Latin Christendom. The Norse were tired of being outside it.

Cross-civ check: the great Norse conversion window (~960–1030) overlaps with the Cluniac monastic reform movement in Latin Christendom (the great spiritual renewal centered on Cluny in Burgundy that would shape European church politics for two centuries), the Buyid rule of Baghdad (Persian Empire Ch 9), the Song dynasty's founding in China (960), the Fatimid Caliphate at the height of its power in Cairo, and the Toltec ascendancy in central Mexico. Iceland's conversion of 1000 happened in the same year that Leif Erikson reached Vinland and that the Hungarian king Stephen I was crowned a Christian king of Hungary by the Pope. The whole western edge of the steppe and Atlantic worlds was being absorbed into Latin Christendom in the same generation. The Vikings' century-long conversion was one front of a continental religious shift.

Viking Age

The World Before the Raids

Lindisfarne and the Western Raids

Conquest and Settlement

East and the Rus'

The Gods and the New God

Skalds, Sagas, Runes

The North Sea Empire and the Long Reach

The Year of Three Kings