The Roman withdrawal from Britton happened in the very early 5th Century, around 408-410. It is generally accepted that the Anglo-Saxon settlement of Britton began shortly thereafter, around 430. Arthurian legend is normally given to take place around the late 5th, early 6th century, so between forty and seventy years later. This leads to the assumption that, at the time of Arthur, teh vast majority of Brittons would have still spoken Brythonic or a slightly mutating Brythonic with Anglo-Saxon influences.
