"I am Rhiannon, daughter of Hyfaidd Hen"
Sculpture of Epona
Creative Commons AttributionSculpture of Epona - Credit: Rosemania

It is believed that many of the characters in The Mabinogion represent the Celtic deities of the pre-Christian era. As the scribes of the manuscripts were probably monks or other religious men, it has  been suggested that they were reluctant to portray the exploits of pagan gods and goddesses, and consequently they downgraded their status  to that of heroes and heroines. 

Sculpture of Epona
GNU Free Documentation LicenseSculpture of Epona - Credit: Owen Cook

 Rhiannon has been linked to: Rigantona, a shadowy Celtic goddess; to Epona, protector of horses and goddess of fertility; and to Dea Matrona, goddess of the River Marne in Gaul, who is sometimes referred to as ‘The Great Mother’. Rhiannon's links with horses are emphasised in this First Branch of the Mabinogi by her magical riding prowess and by the fact that, as part of her punishment, she is forced to carry people on her back as if she were herself a horse.