The Roman Empire pulled out of Britain by the early fifth century, and by about 450, the British economy had essentially collapsed. Britain entered a veritable dark age, with the textual sources we have for the fifth and sixth centuries being able to be counted on one hand. While the Western Roman Empire would collapse by the sixth century, there were several successor states, including a forgotten remnant that survived, according to one argument, until 1282. This was the Kingdom of Gwynedd in Wales, which drew on Roman traditions and memory, and came to an end with the conquests of Edward I. SOURCES: Worlds of Arthur: Facts & Fictions of the Dark Ages, Guy Halsall Britain After Rome, Robin Fleming Arthur's Britain: History and Archaeology AD 367 - 634, Leslie Alcock Britannia Prima: Britain's Last Roman Province, Roger White