Mabinogi
Mabinogion

The Mabinogion is a collection of the earliest Welsh prose stories, compiled in Middle Welsh in the 12th–13th centuries from earlier oral traditions. There are two main source manuscripts, created c. 1350–1410, and a few earlier fragments. Often included in the broader mythologies described as the Matter of Britain, the Mabinogion consists of eleven stories of widely different types, offering drama, philosophy, romance, tragedy, fantasy and humour. Strictly speaking, the Four Branches of the Mabinogi are the main sequence of related tales, but seven others include a classic hero quest, "Culhwch and Olwen"; a historic legend, complete with glimpses of a far off age, in "Lludd and Llefelys"; and other tales portraying a very different King Arthur from the later popular versions.— Wikipedia
