The Fourth Branch of the Mabinogi contains two passages that give a tantalising glimpse of the performance of medieval Welsh narrative. The first tells how Gwydion and his men enter the court of Pryderi, disguised as poets. They receive a great welcome, and Gwydion is given the place of honour at the table, next to Pryderi. When asked for cyfarwyddyd, Gwydion “entertains the court with pleasing ymdiddanau and cyfarwyddyd”; everyone is pleased, because Gwydion is the best cyfarwydd in the world. Later in the tale, and again in the guise of a poet, Gwydion and his host Arianrhod entertain each other with chwedlau and cyfarwyddyd, and again we are informed that Gwydion was a good cyfarwydd.

These passages have been the source of much debate. It is generally held that the term cyfarwyddyd developed from its original sense of “lore, the stuff of stories” to mean simply “tale,” while the cyfarwydd, “the well-informed person, expert,” came to mean simply “storyteller.” The term chwedl (pl. chwedlau), related to the Welsh verb heb, meaning “says, speaks,” is a common word for “tale,” while ymddiddan, “conversation” in Modern Welsh, suggests a specific type of narration—the term occurs in dialogue poems such as Ymddiddan Arthur a’r Eryr [The Dialogue between Arthur and the Eagle], implying perhaps a dramatic performance by two speakers; in the tale of The Lady of the Fountain, on the other hand, ymddiddan is a prose monologue of some length, where Cynon narrates a memorate, a personal experience, to Arthur's knights but directs his comments at Cai, hence it is a dialogue of sorts (although elicits no response from the listener). Ymddiddan, in the sense of conversation, also occurs informally between characters at table. Sometimes, however, a memorate can arise out of such a conversation—as in the case of Matholwch, King of Ireland, who tells his table-companion Bendigeidfran the story of the Cauldron of Rebirth, framing his performance with “I was hunting in Ireland one day,” and signalling an end when he draws the listener back into the conversation with “ ‘And it was then, I suppose, lord,’ said Matholwch to Bendigeidfran, ‘he came over to you.’ “

What becomes immediately apparent is that storytelling was a common occurrence in medieval Wales, and was the domain of both the professional, and the amateur. Moreover, the numerous words for “story, tale” reflect the variety of forms within the genre.