Cornwall forms the westernmost part of the South West Peninsula of the island of Great Britain.The furthest southwestern point of the island is Land's End; the southernmost point is Lizard Point.A large part of the Cornubian batholith is within Cornwall.The north coast has many cliffs where exposed geological formations are studied.After the collapse of the Roman Empire, Cornwall was ruled by chieftains of the Cornovii which may have included semi-historical or legendary figures such as King Mark of Cornwall and King Arthur, evidenced by folklore traditions derived from the Historia Regum Britanniae.The Cornovii division of the Dumnonii tribe were separated from the Brythons of Wales after the Battle of Deorham and often came into conflict with the expanding kingdom of Wessex.King Athelstan in AD 936 set the boundary between English and Cornish at the high water mark of the eastern bank of the River Tamar.From the early Middle Ages, language and culture were shared by Brythons trading across both sides of the Channel, resulting in the corresponding high medieval Breton kingdoms of Domnonée and Cornouaille and the Celtic Christianity common to both areas.
It was formerly a Brythonic kingdom and subsequently a royal duchy.
The administrative centre of Cornwall, and its only city, is Truro.
Cornwall is the homeland of the Cornish people and the cultural and ethnic origin of the Cornish diaspora.
The Cornish nationalist movement contests the present constitutional status of Cornwall and seeks greater autonomy within the United Kingdom in the form of a devolved legislative Cornish Assembly and powers similar to those in Wales and Scotland.
First inhabited in the Palaeolithic and Mesolithic periods, Cornwall continued to be occupied by Neolithic and then Bronze Age peoples, and later (in the Iron Age) by Brythons with strong trade and cultural links to Wales and Brittany.