The old Welsh ( Hen Gymraeg ) is the name given to the Welsh when it was distinguished from the brittonic Langue, probably between the middle of the 6th century and the medium of 7th, until the beginning of the 12th century, date on which it makes place with the Moyen Welsh.

Many poems as some prosodies reached us, generally in later manuscripts, for example the text of Y Gododdin . The oldest text known as old Welsh is probably that engraved on a tomb stone in the church of Tywyn, dated from the beginning of the 8th century. A text in the Livre of Saint Chad is supposed to be written at the end of the 8th century or with the 9th century but it could be a question of a copy of a text of the 6th century or 7th century.

Old Welsh is understandable with a modern Welsh speaker only using grammars and dictionaries.