Excerpt from: "Celtic Literature" Encyclopedia Britainica

"Welsh literature has extended in an unbroken tradition from about the middle of the 6th century to the present day, but, except for two or three short pieces, all pre-Norman poetry has survived only in 12th- to 15th-century manuscripts. Welsh had developed from the older Brythonic by the middle of the 6th century. In the Historia Brittonum (c. 800) references are made to Welsh poets who, if the synchronism is correct, sang in the 6th century. Works by two of them, Taliesin and Aneirin, have survived." Read more 

Poetry

Y Gododin : a poem on the battle of Cattraeth
Book of Taliesin (in Welsh with translation by Meirion Pennar)