Aneirin was an early Medieval Brythonic poet. He is believed to have been a bard or court poet in one of the Cumbric kingdoms of the Hen Ogledd, probably that of Gododdin at Edinburgh, in modern Scotland. The works attributed to Aneirin are preserved in a late-13th-century manuscript known as the Book of Aneirin (or Llyfr Aneirin). The language has been partially modernized into Middle Welsh, but other portions in Old Welsh indicate that at least some of the poetry dates from around Aneirin’s time. The work would have survived through oral transmission until first written down, perhaps in the 9th century. Aneirin’s best known work is Y Gododdin, a series of elegies for the warriors of the northern Brittonic kingdom of Gododdin, circa 600. The poetry abounds in textual difficulties and consequently interpretations vary. One stanza contains what may possibly be the earliest reference to King Arthur.