Y Mabinogion is the oldest surviving body of prose storytelling in Britain — eleven tales of gods, giants, dragons, and troubled marriages, written down in Middle Welsh in the twelfth and thirteenth centuries but rooted in oral tradition centuries older. Several of the mountains, valleys, and forts described elsewhere on this site appear in the tales themselves. This is the whole story, from beginning to end.
What the Mabinogion Is
The eleven tales survive chiefly in two medieval manuscripts: the White Book of Rhydderch, copied around 1350, and the Red Book of Hergest, copied a generation or two later. Nobody wrote "The Mabinogion" as a single book — the title was assembled in the nineteenth century, when the aristocratic scholar Lady Charlotte Guest translated the tales into English between 1838 and 1845 and gave the collection the name by which it has been known ever since. The word itself comes from the Welsh mab, "son" or "boy," and strictly belongs only to the first four tales — the Four Branches of the Mabinogi — each of which ends with the formula "thus ends this branch of the Mabinogi." The other seven tales were gathered alongside them because they share the same world, the same manuscripts, and the same narrative voice.
The standard modern translation is Sioned Davies's 2007 Oxford edition, praised for combining scholarly accuracy with genuine narrative pace — the version worth seeking out if this synopsis leaves you wanting the tales themselves.
The Four Branches of the Mabinogi
The Four Branches are the mythological heart of the collection — four linked tales, almost certainly by a single author, tracing one dynasty of Dyfed across a generation. A single figure, Pryderi, appears in all four, though he is rarely the story's true centre.
First Branch: Pwyll, Prince of Dyfed
Pwyll, prince of Dyfed in southwest Wales, is out hunting when he steals a kill from a pack of ghostly hounds — the Cŵn Annwn, hounds of the Welsh Otherworld. Their owner, Arawn, king of Annwfn, is deeply offended, but rather than take revenge he proposes an exchange: the two men will swap shapes and kingdoms for a year, and Pwyll will fight Arawn's rival Hafgan in his place. Pwyll agrees, rules Annwfn honourably, sleeps chastely beside Arawn's own wife for the full year without touching her, and defeats Hafgan in single combat. Returning to his own body and his own land, he finds Dyfed has flourished under Arawn's unseen rule — and the two kings remain firm allies ever after.
Home again, Pwyll encounters Rhiannon, a woman of unearthly beauty riding a magical horse that no one can catch, however hard they gallop after her. Only when Pwyll simply asks her to stop does she rein in — and reveals that she has chosen him as her husband, against her family's wish to marry her to a suitor named Gwawl. At the wedding feast, Gwawl arrives in disguise and tricks Pwyll into a rash promise, nearly stealing both the feast and the bride. Rhiannon rescues the situation with a trick of her own — a magic bag that can never be filled — luring Gwawl inside it and having him beaten until he renounces his claim.
Rhiannon bears Pwyll a son, but on the night of his birth the child vanishes. Her frightened attendants, fearing punishment, accuse Rhiannon of having murdered and eaten her own baby. Unable to disprove it, she accepts a harsh penance: to sit each day at the castle gate, confessing the false crime to every stranger who passes and offering to carry them on her back like a beast of burden. Meanwhile, far away, a lord named Teyrnon discovers the missing infant and raises him as his own, noticing as the boy grows that he is the image of Pwyll. Teyrnon returns him to Dyfed; Rhiannon's ordeal ends; and the boy is named Pryderi — from pryder, meaning "care" or "anxiety" — for the first words his mother spoke on seeing him again.
Second Branch: Branwen, Daughter of Llŷr
Branwen, sister of the giant-king Bran the Blessed, is married to Matholwch, king of Ireland, sealing an alliance between the two islands. But Bran's troublesome half-brother Efnysien, furious at not being consulted, mutilates Matholwch's horses in an act of calculated insult. Bran pays lavish compensation, including a magical cauldron that restores the dead to life — though those revived can never speak again. It buys only a fragile peace. In Ireland, Branwen bears a son, Gwern, but the Irish nobles' resentment festers; Matholwch is pressured into casting his wife into the kitchens, where she is beaten daily by the court butcher.
Branwen trains a starling to carry a message across the sea to her brother. Bran raises an army and wades the Irish Sea himself, so enormous that ships are barely needed. A fragile truce is arranged and a great hall built to house him — but the Irish hide two hundred armed men inside it, in sacks they claim contain only flour. Efnysien, suspicious, crushes each hidden skull in turn. At the feast that follows, he seizes his infant nephew Gwern and hurls him into the fire. War breaks out immediately, and the Irish use the magic cauldron to revive their fallen again and again — until Efnysien throws himself inside it and, in dying, shatters it beyond repair. The war becomes a massacre: only five pregnant women survive in Ireland to repopulate the island, and only seven men return to Britain. Bran himself, mortally wounded, orders his companions to cut off his head and carry it home for burial in London, promising that it will remain good company on the journey and will not decay. The survivors linger for years in an enchanted feast, first at Harlech — on the Eryri coast, where the castle now stands — and then on the island of Gwales, before Bran's head is finally laid to rest. Branwen, brought back to Wales, dies of grief on the riverbank, undone by all the death her marriage caused.
Third Branch: Manawydan, Son of Llŷr
Manawydan, Branwen's surviving brother and rightful heir to the throne of Britain, finds his claim usurped in his absence. Rather than fight for it, he accepts Pryderi's offer of friendship and lordship in Dyfed, and marries the now-widowed Rhiannon. The two couples — Manawydan and Rhiannon, Pryderi and his wife Cigfa — live contentedly until, without warning, a peal of thunder and a blinding mist strip the land of every living thing except the four of them. Reduced to hunting to survive, they eventually travel into England and prosper as craftsmen — saddlers, shield-makers, cobblers — until local jealousy drives them from town after town.
Back in Dyfed, Pryderi and Manawydan follow a brilliant white boar to a mysterious, deserted fort. Against Manawydan's warning, Pryderi enters and is trapped by an enchanted golden bowl; when Rhiannon goes looking for him, she too is caught. Left alone with Cigfa, Manawydan behaves with scrupulous honour, and the two make a final attempt at a trade in England before returning home to farm. His wheat fields are mysteriously stripped bare by an army of mice — until Manawydan catches one, fat and slow, and prepares to hang it for theft. A scholar, then a priest, then a bishop each appear to beg for the mouse's life. Manawydan refuses every bribe and demands the truth instead: the bishop admits he is really Llwyd, a sorcerer and friend of the humiliated Gwawl, taking revenge for the trick played on him in the First Branch, and the mouse is his own shapeshifted, pregnant wife. Manawydan strikes a bargain — the curse on Dyfed is lifted, and Pryderi and Rhiannon are freed — closing the story with cleverness rather than violence.
Fourth Branch: Math, Son of Mathonwy
In Gwynedd — the kingdom of north Wales that includes Eryri itself — the magician-king Math can only survive with his feet resting in the lap of a virgin, except when at war. His nephew Gilfaethwy desires that maiden, Goewin, and his brother Gwydion — the cleverest sorcerer in the tale — engineers a war with Dyfed as a pretext to draw Math away from his court. Gwydion tricks Pryderi out of a gift of magical swine from the Otherworld, provokes a fight, and kills Pryderi in single combat, while Gilfaethwy rapes Goewin in Math's absence. Returning, Math marries the wronged Goewin himself and punishes both brothers by transforming them, for three years, into breeding pairs of deer, boars, and wolves.
Needing a new virgin footholder, Gwydion proposes his own sister, Arianrhod. Math's magical test of her purity backfires spectacularly: she gives birth on the spot, first to a son who immediately takes to the sea, and then to a shapeless "something" that Gwydion scoops up and secretly raises himself. Humiliated, Arianrhod disowns the second child and lays three curses on him: he will have no name, no weapons, and no human wife unless she herself grants them. Through cunning and disguise, Gwydion tricks her into unknowingly naming the boy Lleu Llaw Gyffes ("bright, skilful hand") and arming him herself. For a wife, Math and Gwydion conjure a woman from the blossoms of oak, broom, and meadowsweet — Blodeuwedd, "flower face" — sidestepping the final curse.
Blodeuwedd falls deeply in love with a neighbouring lord, Gronw Pebr, and the two plot to kill her husband. She wheedles out of Lleu the elaborate, near-impossible conditions under which alone he can be harmed, and passes them to her lover. Gronw wounds Lleu exactly so — and Lleu, rather than dying, transforms into an eagle and flies off. Gwydion tracks him down, wasting and half-rotten, perched high in a tree, and sings him gradually back into human form. Restored, Lleu is entitled by law to strike Gronw a single blow in return; Gronw begs to shelter behind a stone, but Lleu's spear passes clean through the rock and kills him anyway. Gwydion, for her part in the betrayal, transforms Blodeuwedd into an owl — a bird shunned and mobbed by all others, forever.
The Four Native Tales
Alongside the Four Branches sit four independent tales, closer to legend and folk-tale than to structured myth, but set in the same landscape and often touching the same history.
The Dream of Macsen Wledig
The Roman emperor Macsen — a romanticised version of the real fourth-century usurper Magnus Maximus — dreams of a journey across mountains and rivers to a golden hall, where he falls in love with a maiden of extraordinary beauty. Waking obsessed, he refuses food and company until his messengers scour the empire and finally identify the place from his dream: Segontium, the Roman fort at Caernarfon, on the western edge of Eryri. There they find the maiden, Elen, daughter of a local chieftain. Macsen marries her, and grants her father sovereignty over Britain in return. Elen — remembered in later tradition as Elen Luyddog, "Elen of the Hosts" — asks in turn for great roads to be built connecting the forts of Wales, so that soldiers might march swiftly between them. Those roads survive today as Sarn Helen, the Roman road threading south from Caernarfon through Dolgellau and beyond — a legend, in this one case, with tarmac and trackbed you can actually walk.
Lludd and Llefelys
Lludd, king of Britain shortly before the Roman conquest, must overcome three plagues afflicting his kingdom with the help of his brother Llefelys, king of France. The first plague is a race called the Coranians, who can hear every word spoken anywhere in Britain, making rebellion against them impossible — defeated only by a specially brewed potion, harmless to Britons, thrown over the whole assembled population at once. The second is a terrifying annual scream, heard every May Eve, caused by a native red dragon locked in an endless, exhausting battle with an invading white dragon. Lludd traps both combatants by luring them with a vat of mead at the exact centre of the island, and once they fall into a drunken sleep, wraps them in cloth and buries them, still sleeping, in a stone chest at the safest place he knows in the whole kingdom: Dinas Emrys, in the hills above Nantgwynant in the heart of Eryri. It is the same hill, and the same sleeping dragons, later woven into the story of Vortigern and the boy-prophet Myrddin (Merlin) — the tale that gives Wales its red dragon flag. The third plague, a magician who casts the entire court into enchanted sleep before making off with its stores, is defeated simply: Lludd stays awake in a vat of cold water, and confronts the thief when he comes.
Culhwch and Olwen
The longest and wildest of the eleven tales. Cursed by a jealous stepmother to marry no one but Olwen, daughter of the giant Ysbaddaden, the young Culhwch — who has never even seen her — sets off to find his kinsman King Arthur and beg his help. Arthur agrees, and sends an extraordinary company of warriors after her, including Cai (the model for later legend's Sir Kay) and Bedwyr (the future Sir Bedivere). Ysbaddaden cannot survive his daughter's wedding, and so sets Culhwch some forty apparently impossible tasks before he will consent to it — among them freeing the imprisoned Mabon from an ancient dungeon, and hunting down the monstrous boar Twrch Trwyth, once a king transformed, across the length of Wales. Only a portion of the tasks are actually narrated, in a cascade of episodes, digression, and sheer inventive excess, but the giant is eventually killed and Olwen is freed to marry the man who never gave up on her.
The Dream of Rhonabwy
Sent to hunt down a rebellious prince, the knight Rhonabwy and his companions take shelter for the night in a filthy, flea-ridden farmhouse. Rhonabwy alone sleeps on a yellow calfskin — and it carries him three days and nights into a vivid dream of the age of Arthur. He is led by the warrior Iddawg, self-confessed instigator of the catastrophic battle of Camlann, into Arthur's own court, where the king laments how diminished Britain's men have become since his day. Rhonabwy watches Arthur and the knight Owain play a board game while, outside, ravens and soldiers fight an escalating, almost absurd battle around them — a scene most scholars read as satire rather than heroism, needling both the golden Arthurian past and the diminished present it is being compared to. Rhonabwy wakes on the same calfskin, having experienced what felt like years in a single night. A note at the tale's end declares that no storyteller could ever recite the whole dream from memory alone — it is simply too dense with detail — which is very likely why it survives as a written text rather than an oral one.
The Three Welsh Romances
The final three tales are full Arthurian romances, telling stories that also appear, in different form, in the French poems of Chrétien de Troyes — scholars still debate whether the Welsh versions are the source, a parallel retelling, or a later adaptation, but all agree the Welsh tales stand as substantial literature in their own right.
Owain, or the Lady of the Fountain
The knight Owain hears of a magic fountain that summons a fearsome storm and its guardian knight when water is poured on a nearby stone. He defeats the guardian, marries his widow — the Lady of the Fountain — and takes on the role himself. Drawn back to Arthur's court and forgetting his promise to return within three years, Owain is publicly shamed by his abandoned wife's messenger and driven mad with grief, living wild in the forest until healing ointment restores him. He rescues a lion from a battle with a serpent, and the grateful animal becomes his constant companion, helping him complete a further string of rescues and adventures before husband and wife are finally reconciled.
Geraint and Enid
Geraint, a knight of Arthur's court, marries the beautiful and devoted Enid. Overhearing her innocently lament that their married contentment may have made him lazy and unworthy of his reputation, he misreads her words as a confession of infidelity. In a jealous fury, he drags her on a long, dangerous journey, forbidding her to speak to him under any circumstances — yet she repeatedly breaks his order to warn him of ambushes and danger along the way, at real risk to herself. Only gradually, through her unwavering loyalty in the face of his unfairness, does Geraint recognise how wrongly he has treated her, and the two are reconciled as equals.
Peredur, Son of Efrawg
Raised in isolation by his widowed mother, deliberately kept ignorant of knighthood after his father and brothers died in tournament and war, the naive Peredur stumbles across three of Arthur's knights in the forest and mistakes them for angels. Determined to become like them, he leaves for Arthur's court and is mocked for his rustic ignorance — until his raw natural ability begins to show. His adventures grow steadily stranger: a fortress of nine witches who train him in arms, a mysterious procession bearing a bleeding spear and a platter holding a severed head, a devoted and remarkable woman named Angharad Golden-Hand whom he swears never to speak to again until public opinion of him improves. The tale is the most tangled and dreamlike of the eleven, and its bleeding-spear-and-platter procession is often discussed by scholars alongside the later, more famous Grail imagery of French Arthurian romance.
Why the Mabinogion Still Matters in Eryri
These are not stories imported into Wales from elsewhere — they were told, in Welsh, about this particular landscape, centuries before anyone wrote them down. Dinas Emrys, the low wooded hill above Nantgwynant, is not simply the setting for one story but for two: the dragons of Lludd and Llefelys are the very same dragons that Vortigern's men later dig up in the tale of Myrddin. Harlech Castle stands on the site remembered as Bran's court in the Second Branch. Sarn Helen, Elen's road from the Dream of Macsen Wledig, can still be walked south from Caernarfon toward Dolgellau. None of this is coincidence — it is what happens when a literature and a landscape have never been separated. Reading even one branch before setting out for Nantgwynant, Harlech, or Caernarfon changes what those places are — turning hillside and castle wall back into the stage they were always written to be.
Independently written — Snowdon.com