Common Brittonic (Old English: Brytisċ; Welsh: Brythoneg; Cornish: Brythonek; Breton: Predeneg) was a Celtic language spoken in Britain and Brittany. It is also variously known as Old Brittonic, and Common or Old Brythonic. It is a form of Insular Celtic, descended from Proto-Celtic, a theorized parent tongue that, by the first half of the first millennium BC, was diverging into separate dialects or languages. Pictish is linked, likely as a sister language or a descendant branch.