This branch introduces a number of storylines that reappear in later tales, including the alliance between Dyfed and Annwn, and the enmity between Pwyll and Gwawl.

Whilst hunting in Glyn Cuch, Pwyll, prince of Dyfed becomes separated from his companions and stumbles across a pack of hounds feeding on a slain stag.

Some time later, Pwyll and his noblemen ascend the mound of Gorsedd Arberth and witness the arrival of Rhiannon, appearing to them as a beautiful woman dressed in gold silk brocade and riding a shining white horse.

The man then reveals himself as Gwawl ap Clud and asks for Rhiannon and the wedding feast, which Pwyll is obliged to give.

Rhiannon, unhappy with this turn of events explains that the feast is hers and not Pwyll's to give away and it has already been promised to the guests and hosts.

She explains that after another year an equal feast will be prepared for her and Gwawl ap Clud, and he leaves back to his realm.

Under the advice of his noblemen, Pwyll and Rhiannon attempt to supply an heir to the kingdom and eventually a boy is born.

To avoid the king's wrath, the ladies smear dog's blood onto a sleeping Rhiannon, claiming that she had committed infanticide and cannibalism through eating and "destroying" her child.