sentences:  Before this, a personal union had existed between these two countries since the 1603 Union of the Crowns under James VI of Scotland and I of England.Great Britain was probably first inhabited by those who crossed on the land bridge from the European mainland.Human footprints have been found from over 800,000 years ago in Norfolk and traces of early humans have been found (at Boxgrove Quarry, Sussex) from some 500,000 years ago and modern humans from about 30,000 years ago.