The first four tales are about Prince Pryderi, its next four are unrelated stories, and it concludes with three Arthurian romances.
Lady Charlotte Elizabeth Guest wrote its first English translation in 1839, and she gave it its popular title by adopting a variation of the collective name of its first four stories.  It is preserved in two manuscripts, the Red Book of Hergest and the older White Book of Rhyddrech.  The first four tales are about Prince Pryderi, its next four are unrelated stories, and it concludes with three Arthurian romances. For ten points, identify this collection of 11th to 13th century Welsh prose tales.
Lady Charlotte Elizabeth Guest wrote its first English translation in 1839, and she gave it its popular title by adopting a variation of the collective name of its first four stories.  
Mabinogion