For the purposes of this article, Prehistoric Britain is Britain during the period between the first arrival of humans on the land mass now known as Great Britain and the start of recorded British history. The "recorded history" of Britain is conventionally reckoned to begin in AD 43 with the Roman invasion of Britain, though some historical information is available from before then.
Archaeological prehistory, which comprises the bulk of this article, is commonly divided into distinct chronological periods. These are based on the development of tools, from stone to bronze and iron, as well as changes in culture and climate that can be determined from the archaeological record. The boundaries of these periods are uncertain, as the changes between them are gradual. In addition, the dates of these changes demonstrated in Britain are generally different from those of Continental Europe.
Britain has been intermittently inhabited by members of the Homo genus for hundreds of thousands of years, and by Homo sapiens for tens of thousands of years. DNA analysis has shown that modern humans have periodically occupied Britain for at least 41,500 years, since before the end of the last glacial period. This evidence also shows that as the last glacial period encroached from the north, the first humans living in Britain either died out or retreated to Southern Europe when much of the continental land mass of Britain became covered with ice or frozen as tundra.