There are something like 250 names mentioned in this one astonishing passage from the Mabinogion (please, don't even try and read it - I have just provided the text to give you a feel for what it looks like). One can only marvel to think that the Celtic bards used to learn this (and all the rest of the Mabinogion) by heart and have to repeat it flawlessly before being considered qualified. I have to wonder, what messages are there hidden in the text, why just those names and in that order?

And Arthur took a golden comb, and scissors, whereof the loops were of silver, and he combed his hair.  And Arthur inquired of him who he was.  “For my heart warms unto thee, and I know that thou art come of my blood.  Tell me, therefore, who thou art.”  “I will tell thee,” said the youth.  “I am Kilhwch, the son of Kilydd, the son of Prince Kelyddon, by Goleuddydd, my mother, the daughter of Prince Anlawdd.”  “That is true,” said Arthur; “thou art my cousin.  Whatsoever boon thou mayest ask, thou shalt receive, be it what it may that thy tongue shall name.”  “Pledge the truth of Heaven and the faith of thy kingdom thereof.”  “I pledge it thee, gladly.”  “I crave of thee then, that thou obtain for me Olwen, the daughter of Yspaddaden Penkawr; and this boon I likewise seek at the hands of thy warriors.  I seek it from Kai, and Bedwyr, and Greidawl Galldonyd, and Gwythyr the son of Greidawl, and Greid the son of Eri, and Kynddelig Kyvarwydd, and Tathal Twyll Goleu, and Maelwys the son of Baeddan, and Crychwr the son of Nes, and Cubert the son of Daere, and Percos the son of Poch, and Lluber Beuthach, and Corvil Bervach, and Gwynn the son of Nudd, and Edeyrn the son of Nudd, and Gadwy the son of Geraint, and Prince Fflewddur Fflam, and Ruawn Pebyr the son of Dorath, and Bradwen the son of Moren Mynawc, and Moren Mynawc himself, and Dalldav the son of Kimin Côv, and the son of Alun Dyved, and the son of Saidi, and the son of Gwryon, and Uchtryd Ardywad Kad, and Kynwas Curvagyl, and Gwrhyr Gwarthegvras, and Isperyr Ewingath, and Gallcoyt Govynynat, and Duach, and Grathach, and Nerthach, the sons of Gwawrddur Kyrvach (these men came forth from the confines of hell), and Kilydd Canhastyr, and Canastyr Kanllaw, and Cors Cant-Ewin, and Esgeir Gulhwch Govynkawn, and Drustwrn Hayarn, and Glewlwyd Gavaelvawr, and Lloch Llawwynnyawc, and Aunwas Adeiniawc, and Sinnoch the son of Seithved, and Gwennwynwyn the son of Naw, and Bedyw the son of Seithved, and Gobrwy the son of Echel Vorddwyttwll, and Echel Vorddwyttwll himself, and Mael the son of Roycol, and Dadweir Dallpenn, and Garwyli the son of Gwythawc Gwyr, and Gwythawc Gwyr himself, and Gormant the son of Ricca, and Menw the son of Teirgwaedd, and Digon the son of Alar, and Selyf the son of Smoit, and Gusg the son of Atheu, and Nerth the son of Kedarn, and Drudwas the son of Tryffin, and Twrch the son of Perif, and Twrch the son of Annwas, and Iona king of France, and Sel the son of Selgi, and Teregud the son of Iaen, and Sulyen the son of Iaen, and Bradwen the son of Iaen, and Moren the son of Iaen, and Siawn the son of Iaen, and Cradawc the son of Iaen.  (They were men of Caerdathal, of Arthur’s kindred on his father’s side.)  Dirmyg the son of Kaw, and Justic the son of Kaw, and Etmic the son of Kaw, and Anghawd the son of Kaw, and Ovan the son of Kaw, and Kelin the son of Kaw, and Connyn the son of Kaw, and Mabsant the son of Kaw, and Gwyngad the son of Kaw, and Llwybyr the son of Kaw, and Coth the son of Kaw, and Meilic the son of Kaw, and Kynwas the son of Kaw, and Ardwyad the son of Kaw, and Ergyryad the son of Kaw, and Neb the son of Kaw, and Gilda the son of Kaw, and Calcas the son of Kaw, and Hueil the son of Kaw (he never yet made a request at the hand of any Lord).  And Samson Vinsych, and Taliesin the chief of the bards, and Manawyddan the son of Llyr, and Llary the son of Prince Kasnar, and Ysperni the son of Fflergant king of Armorica, and Saranhon the son of Glythwyr, and Llawr Eilerw, and Annyanniawc the son of Menw the son of Teirgwaedd, and Gwynn the son of Nwyvre, and Fflam the son of Nwyvre, and Geraint the son of Erbin, and Ermid the son of Erbin, and Dyvel the son of Erbin, and Gwynn the son of Ermid, and Kyndrwyn the son of Ermid, and Hyveidd Unllenn, and Eiddon Vawr Vrydic, and Reidwn Arwy, and Gormant the son of Ricca (Arthur’s brother by his mother’s side; the Penhynev of Cornwall was his father), and Llawnrodded Varvawc, and Nodawl Varyf Twrch, and Berth the son of Kado, and Rheidwn the son of Beli, and Iscovan Hael, and Iscawin the son of Panon, and Morvran the son of Tegid (no one struck him in the battle of Camlan by reason of his ugliness; all thought he was an auxiliary devil.  Hair had he upon him like the hair of a stag).  And Sandde Bryd Angel (no one touched him with a spear in the battle of Camlan because of his beauty; all thought he was a ministering angel).  And Kynwyl Sant (the third man that escaped from the battle of Camlan, and he was the last who parted from Arthur on Hengroen his horse).  And Uchtryd the son of Erim, and Eus the son of Erim, and Henwas Adeinawg the son of Erim, and Henbedestyr the son of Erim, and Sgilti Yscawndroed the son of Erim. (Unto these three men belonged these three qualities, - With Henbedestyr there was not any one who could keep pace, either on horseback or on foot; with Henwas Adeinawg, no four-footed beast could run the distance of an acre, much less could it go beyond it; and as to Sgilti Yscawndroed, when he intended to go upon a message for his Lord, he never sought to find a path, but knowing whither he was to go, if his way lay through a wood he went along the tops of the trees.  During his whole life, a blade of reed grass bent not beneath his feet, much less did one ever break, so lightly did he tread.)  Teithi Hên the son of Gwynhan (his dominions were swallowed up by the sea, and he himself hardly escaped, and he came to Arthur; and his knife had this peculiarity, that from the time that he came there no haft would ever remain upon it, and owing to this a sickness came over him, and he pined away during the remainder of his life, and of this he died).  And Carneddyr the son of Govynyon Hên, and Gwenwynwyn the son of Nav Gyssevin, Arthur’s champion, and Llysgadrudd Emys, and Gwrbothu Hên (uncles unto Arthur were they, his mother’s brothers).  Kulvanawyd the son of Goryon, and Llenlleawg Wyddel from the headland of Ganion, and Dyvynwal Moel, and Dunard king of the North, Teirnon Twryf Bliant, and Tegvan Gloff, and Tegyr Talgellawg, Gwrdinal the son of Ebrei, and Morgant Hael, Gwystyl the son of Rhun the son of Nwython, and Llwyddeu the son of Nwython, and Gwydre the son of Llwyddeu (Gwenabwy the daughter of [Kaw] was his mother, Hueil his uncle stabbed him, and hatred was between Hueil and Arthur because of the wound).  Drem the son of Dremidyd (when the gnat arose in the morning with the sun, he could see it from Gelli Wic in Cornwall, as far off as Pen Blathaon in North Britain).  And Eidyol the son of Ner, and Glwyddyn Saer (who constructed Ehangwen, Arthur’s Hall).  Kynyr Keinvarvawc (when he was told he had a son born he said to his wife, ‘Damsel, if thy son be mine, his heart will be always cold, and there will be no warmth in his hands; and he will have another peculiarity, if he is my son he will always be stubborn; and he will have another peculiarity, when he carries a burden, whether it be large or small, no one will be able to see it, either before him or at his back; and he will have another peculiarity, no one will be able to resist fire and water so well as he will; and he will have another peculiarity, there will never be a servant or an officer equal to him’).  Henwas, and Henwyneb (an old companion to Arthur).  Gwallgoyc (another; when he came to a town, though there were three hundred houses in it, if he wanted anything, he would not let sleep come to the eyes of any one whilst he remained there).  Berwyn the son of Gerenhir, and Paris king of France, and Osla Gyllellvawr (who bore a short broad dagger.  When Arthur and his hosts came before a torrent, they would seek for a narrow place where they might pass the water, and would lay the sheathed dagger across the torrent, and it would form a bridge sufficient for the armies of the three Islands of Britain, and of the three islands adjacent, with their spoil).  Gwyddawg the son of Menestyr (who slew Kai, and whom Arthur slew, together with his brothers, to revenge Kai).  Garanwyn the son of Kai, and Amren the son of Bedwyr, and Ely Amyr,and Rheu Rhwyd Dyrys, and Rhun Rhudwern, and Eli, and Trachmyr (Arthur’s chief huntsmen).  And Llwyddeu the son of Kelcoed, and Hunabwy the son of Gwryon, and Gwynn Godyvron, and Gweir Datharwenniddawg, and Gweir the son of Cadell the son of Talaryant, and Gweir Gwrhyd Ennwir, and Gweir Paladyr Hir (the uncles of Arthur, the brothers of his mother).  The sons of Llwch Llawwynnyawg (from beyond the raging sea).  Llenlleawg Wyddel, and Ardderchawg Prydain.  Cas the son of Saidi, Gwrvan Gwallt Avwyn, and Gwyllennhin the king of France, and Gwittart the son of Oedd king of Ireland.  Garselit Wyddel, Panawr Pen Bagad, and Ffleudor the son of Nav, Gwynnhyvar mayor of Cornwall and Devon (the ninth man that rallied the battle of Camlan).  Keli and Kueli, and Gilla Coes Hydd (he would clear three hundred acres at one bound: the chief leaper of Ireland was he).  Sol, and Gwadyn Ossol, and Gwadyn Odyeith.  (Sol could stand all day upon one foot.  Gwadyn Ossol, if he stood upon the top of the highest mountain in the world, it would become a level plain under his feet.  Gwadyn Odyeith, the soles of his feet emitted sparks of fire when they struck upon things hard, like the heated mass when drawn out of the forge.  He cleared the way for Arthur when he came to any stoppage.)  Hirerwm and Hiratrwm.  (The day they went on a visit three Cantrevs provided for their entertainment, and they feasted until noon and drank until night, when they went to sleep.  And then they devoured the heads of the vermin through hunger, as if they had never eaten anything.  When they made a visit they left neither the fat nor the lean, neither the hot nor the cold, the sour nor the sweet, the fresh nor the salt, the boiled nor the raw.)  Huarwar the son of Aflawn (who asked Arthur such a boon as would satisfy him.  It was the third great plague of Cornwall when he received it.  None could get a smile from him but when he was satisfied).  Gware Gwallt Euryn.  The two cubs of Gast Rhymi, Gwyddrud and Gwyddneu Astrus.  Sugyn the son of Sugnedydd (who would suck up the sea on which were three hundred ships so as to leave nothing but a dry strand.  He was broad-chested).  Rhacymwri, the attendant of Arthur (whatever barn he was shown, were there the produce of thirty ploughs within it, he would strike it with an iron flail until the rafters, the beams, and the boards were no better than the small oats in the mow upon the floor of the barn).  Dygyflwng and Anoeth Veidawg.  And Hir Eiddyl, and Hir Amreu (they were two attendants of Arthur).  And Gwevyl the son of Gwestad (on the day that he was sad, he would let one of his lips drop below his waist, while he turned up the other like a cap upon his head).  Uchtryd Varyf Draws (who spread his red untrimmed beard over the eight-and-forty rafters which were in Arthur’s Hall).  Elidyr Gyvarwydd.  Yskyrdav and Yscudydd (two attendants of Gwenhwyvar were they.  Their feet were swift as their thoughts when bearing a message).  Brys the son of Bryssethach (from the Hill of the Black Fernbrake in North Britain).  And Grudlwyn Gorr.  Bwlch, and Kyfwlch, and Sefwlch, the sons of Cleddyf Kyfwlch, the grandsons of Cleddyf Difwlch.  (Their three shields were three gleaming glitterers; their three spears were three pointed piercers; their three swords were three grinding gashers; Glas, Glessic, and Gleisad.  Their three dogs, Call, Cuall, and Cavall.  Their three horses, Hwyrdyddwd, and Drwgdyddwd, and Llwyrdyddwg.  Their three wives, Och, and Garym, and Diaspad.  Their three grandchildren, Lluched, and Neved, and Eissiwed.  Their three daughters, Drwg, and Gwaeth, and Gwaethav Oll.  Their three hand-maids, Eheubryd the daughter of Kyfwlch, Gorascwrn the daughter of Nerth, Ewaedan the daughter of Kynvelyn Keudawd Pwyll the half-man.)  Dwnn Diessic Unbenn, Eiladyr the son of Pen Llarcau, Kynedyr Wyllt the son of Hettwn Talaryant, Sawyl Ben Uchel, Gwalchmai the son of Gwyar, Gwalhaved the son of Gwyar, Gwrhyr Gwastawd Ieithoedd (to whom all tongues were known), and Kethcrwm the Priest.  Clust the son of Clustveinad (though he were buried seven cubits beneath the earth, he would hear the ant fifty miles off rise from her nest in the morning).  Medyr the son of Methredydd (from Gelli Wic he could, in a twinkling, shoot the wren through the two legs upon Esgeir Oervel in Ireland).  Gwiawn Llygad Cath (who could cut a haw from the eye of the gnat without hurting him).  Ol the son of Olwydd (seven years before he was born his father’s swine were carried off, and when he grew up a man he tracked the swine, and brought them back in seven herds).  Bedwini the Bishop (who blessed Arthur’s meat and drink).  For the sake of the golden-chained daughters of this island.  For the sake of Gwenhwyvar its chief lady, and Gwennhwyach her sister, and Rathtyeu the only daughter of Clemenhill, and Rhelemon the daughter of Kai, and Tannwen the daughter of Gweir Datharwenîddawg.  Gwenn Alarch the daughter of Kynwyl Canbwch.  Eurneid the daughter of Clydno Eiddin.  Eneuawc the daughter of Bedwyr.  Enrydreg the daughter of Tudvathar.  Gwennwledyr the daughter of Gwaledyr Kyrvach.  Erddudnid the daughter of Tryffin.  Eurolwen the daughter of Gwdolwyn Gorr.  Teleri the daughter of Peul.  Indeg the daughter of Garwy Hir.  Morvudd the daughter of Urien Rheged.  Gwenllian Deg the majestic maiden.  Creiddylad the daughter of Lludd Llaw Ereint.  (She was the most splendid maiden in the three Islands of the mighty, and in the three Islands adjacent, and for her Gwythyr the son of Greidawl and Gwynn the son of Nudd fight every first of May until the day of doom.)  Ellylw the daughter of Neol Kynn-Crog (she lived three ages).  Essyllt Vinwen and Essyllt Vingul.”  And all these did Kilhwch the son of Kilydd adjure to obtain his boon.