We all like to know where we’ve come from. Origin myths are important for all peoples. Until the sixteenth century, the two most influential explanations were written down in the eleventh and twelfth centuries though their origins lie centuries earlier. Geoffrey of Monmouth wrote his Historia Regum Britanniae, (History of the Kings of Britain) during the mid-to-late 1130s and said that the first inhabitants of Britain were giants led by Albion. Later, Greeks under Brutus landed at Totnes and defeated the giants ruling the country until the Romans arrived.  In Ireland, the Lebor Gabála Érenn, (The Book of the Taking of Ireland) was compiled in the eleventh century by an anonymous scholar and too provides origin myths chronicling four mythical phases of immigration, with six invasions.  The last of these was by the Gaels, descendants of a Scythian king from what is now eastern Ukraine who had settled in the Iberian Peninsula.
We do not know with any precision when, how, why or which early peoples arrived in Britain and Ireland or whether they arrived, left or died out when climatic conditions proved intolerable and later returned. 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. Just when historians have reached tentative conclusions, new archaeological evidence is found that forces revision of the chronology. In April 2003, 32 worked flints were found at Pakefield on the Suffolk coast that were dated to about 700,000 years ago but seven years later, the discovery of 70 flint tools in eroded cliffs at Happisburgh in Norfolk pushing back the arrival of people a further 100,000 years.  Although they have no concrete evidence, scientists believe the people must have been able to make clothes, shelters and possibly fires to survive the winters. Homo antecessor, known as ‘Pioneer Man’, has previously been found at Sima del Elefante and Atapuerca in northern Spain and is also known to have lived around 800,000 years ago and this early human could be a candidate for the tools’ maker.
Archaeology provides some indication of which human species arrived in Britain but the record in limited. Evidence from Boxgrove in Sussex illustrates the arrival of an archaic Homo species called Homo heidelbergensis around 500,000 years ago. These early peoples made flint tools such as hand axes and hunted the large native mammals of the period driving them over the tops of cliffs or into bogs to more easily kill them. The extreme cold of the following Anglian Stage is likely to have driven humans out of Britain altogether and the region does not appear to have been occupied again until the ice receded. . This warmer climate lasted from around 300,000 until 200,000 years ago and saw flint tool industry develop at sites such as Barnfield Pit in Kent. This period saw also Levallois flint tools introduced possibly by people arriving from Africa though finds from Swanscombe and Botany Pit in Purfleet suggest Levallois technology was a European rather than African introduction. The more advanced flint technology enabled more efficient hunting and made Britain a more worthwhile place to remain until the climate again cooled. There appears to have been a gradual decline in population suggesting that the absence of humans in the archaeological record here was the result of gradual depopulation.
From 180,000 to 60,000, there is no evidence of human occupation in Britain. Meltwaters from the previous glaciation cut Britain off from the continent for the first time during this period and this may explain the lack of activity. From 60,000 to 40,000 Britain was primarily grassland with giant deer, horses, woolly mammoths, rhino and carnivores. Neanderthal man had arrived in Britain by around 40,000 years ago though evidence of their occupation of Britain is limited and by 30,000 BC the first signs of modern human (Homo sapiens) activity are known. The most famous example from this period is the burial of the ‘Red Lady of Paviland’, who was actually a man coastal south Wales. A final Ice Age covered Britain between around 70,000 and 10,000 years ago with an extreme cold snap between 22,000 and 13,000 years ago. Sites such as Gough’s Cave in Somerset dated at 12,000 BC provide evidence suggesting that humans returned to Britain towards the end of this Ice Age, though further extremes of cold immediately before the final thaw may have caused them to leave again and then return repeatedly. From 12,700 to 11,500 BC, the climate became cooler and drier, food animal populations seem to have declined although woodland coverage expanded. Tool manufacture now revolved around smaller flints but bone and antler work became less common. Typically there are parallel-sided flint blades known as ‘Cheddar Points’. There are scrapers, some of which are annotated with what may be calendars. However, the number of known sites is much larger than before and more widely spread. Many more open air sites are known such as that at Hengistbury Head
The story of ancient Britain is traditionally seen as one of successive waves of settlers from the continent, bringing with them new cultures and technologies. Located at the fringes of Europe, Britain received technological and cultural developments much later than mainland areas. DNA analysis has shown that modern humans arrived in Britain before the last Ice Age but retreated to Southern Europe when much of Britain was covered in glaciers, with the remainder being tundra. At this time, the sea level was about over 400 feet lower than it is today and Britain was joined to Ireland and to the continent of Europe facilitating the movement of peoples. Many of the changes that occurred in British society are now seen as a result of the native inhabitants adopting foreign customs rather than being subsumed by an invading population. Around 10,000 years ago the Ice Age finally ended, temperatures rose, probably to levels similar to those today, and forests expanded further. After the end of the last Ice Age, around 9500 BC, as sea levels rose Ireland became separated from Britain and 3000 years later, Britain was cut off from continental Europe. More recent archaeological theories have questioned the emphasis on migration suggesting a more complex relationship between Britain and the continent.
Humans spread and reached the far north of Scotland during this period. Sites from the British Mesolithic include the Mendips, Star Carr in Yorkshire and Oronsay in the Inner Hebrides. Excavations at Howick in Northumberland uncovered evidence of a large circular building dating to c7600 BC that has been interpreted as a dwelling. A further example has also been identified at Deepcar in Sheffield, and a building dating to c. 8500 BC was discovered at the Star Carr site. The older view that Mesolithic Britons were nomadic is now being replaced with a more complex picture of seasonal occupation or in some cases, permanent occupation. Travel distances seem to have become shorter with movement limited between high and low ground. The Mesolithic environment enabled population to grow but its success in exploiting that environment eventually led to local exhaustion of many natural resources. A few Neolithic monuments overlie Mesolithic sites but little continuity can be demonstrated. Farming of crops and domestic animals was adopted in Britain around 4500 BC at least partly because of the need for reliable food sources. Hunter-gathering persisted into the Neolithic at first but the increasing sophistication of material culture with the attendant control of local resources by individual groups would have caused it to be replaced by distinct territories occupied by different tribes. Other elements of the Neolithic such as pottery, leaf-shaped arrowheads and polished stone axes would have been adopted earlier.
The earliest evidence of human occupation of Ireland after the retreat of the ice has been dated to around 8000 BC. During the Mesolithic the population of Ireland was probably never more than a few thousand. Evidence for Mesolithic hunter-gatherers have been found throughout the country: a number of the key Early Mesolithic excavations are the settlement site at Coleraine in County Londonderry; the cremations at Hermitage, County Limerick on the bank of the River Shannon; and the camp site at Lough Boora in County Offaly. It is thought that these settlers first colonised the northeast of the country from Scotland. Although sea levels were still lower than they are today, Ireland may already have been an island by the time the first settlers arrived by boat and most of the Mesolithic sites in Ireland are coastal settlements.
In both Britain and Ireland, the Neolithic saw the domestication of animals and plants, the development of farming and a more sedentary way of life. Reliable and predictable food supplies led to growing functional divisions in society between farmers, artisans and leaders supported by specialised military support. Forest clearances were undertaken to provide room for cereal cultivation and animal herds. Native cattle and pigs were reared whilst sheep and goats were later introduced from the continent as were the wheats and barleys grown in Britain. However, only a few actual settlement sites are known in Britain, unlike the continent and cave occupation remained common at this time. Although there remain some differences between historians on the part played by migration, genetic analysis suggests that continental invaders played an important role in the development of the Neolithic Revolution. The construction of the earliest earthwork sites in Britain began during the early Neolithic (c4400-3300 BC) in the form of long barrows used for communal burial and the first causewayed enclosures, sites that have parallels on the continent. The former may be derived from the long house although no long house villages have been found in Britain, only individual examples. The stone-built houses on Orkney such as those at Skara Brae are however indicators of some nucleated settlement in Britain. The Middle Neolithic (c3300 BC-c2900 BC) saw the development of cursus monuments close to earlier barrows and the growth and abandonment of causewayed enclosures as well as the building of impressive chamber tombs like that at West Kennett and the earliest stone circles and individual burials also appeared. During the later Neolithic (c2900-c2200 BC), new enclosures, called henges were built, along with stone rows and the sites of Stonehenge, Avebury and Silbury Hill reached their peak. Industrial flint mining such as that at Grimes Graves began, with evidence of long distance trade. 
Around 2700 BC, a new pottery style along with flat axes and more individual burial practices arrived in Britain, often referred to as the Beaker culture. Whether the ‘Beaker’ people were a race of people who migrated to Britain from the continent or whether Beaker culture had spread across Europe to Britain through trade across tribal boundaries is unclear, but integration with existing peoples appears to have been peaceful. People of this period were also largely responsible for building many famous prehistoric sites such as the later phases of Stonehenge along with Seahenge. The skill of refining metal, initially developed in Spain or Portugal, was part of Beaker culture and between 2150 BC and 2000 BC, bronze gradually replaced stone as the main material for tool and weapon making. With its large reserves of tin in Devon and Cornwall and copper in north Wales, intensive mining developed and by 1600 BC, an extensive trading system that extended across Europe in tin and copper had developed. Increased levels of rain made Britain wetter and saw population move away from the easily defensible hills on to the more vulnerable fertile plains. This was accompanied by the emergence of large livestock farms in the lowlands that contributed to significant economic growth. Social groups appear to have become more tribal in character and social hierarchies, already in existence, became more pronounced. 
There is evidence of a relatively large scale disruption of cultural patterns which some scholars think may indicate an invasion or at least a migration into southern Great Britain circa the 12th century BC. This disruption was felt far beyond Britain, even beyond Europe, as most of the great Near Eastern empires collapsed or experienced severe difficulties and the Sea Peoples harried the entire Mediterranean basin around this time. Some scholars consider that the Celtic languages arrived in Britain at this time.  Attempts to understand the human behaviour of the period have traditionally focused on the geographic position of the islands and their landscape, along with the channels of influence coming from continental Europe. During the later Bronze Age there are indications of new ideas about land use and settlement. Extensive field systems, now called Celtic fields, were being set out and settlements becoming more permanent and focused on better exploitation of the land. The central organisation to undertake this had been present since the Neolithic period but it was now being targeted at economic and social goals and in taming the landscape rather than in building large ceremonial structures such as Stonehenge. Long ditches, some many miles in length, were dug with enclosures placed at their ends. These are thought to indicate territorial borders and a desire to increase control over wide areas.
By the 8th century BC, there is increasing evidence of Great Britain being closely tied to continental Europe especially in the south and east. New weapon types appeared with clear parallels to those on the continent. Phoenician traders probably began visiting Great Britain in search of minerals around this time, bringing with them goods from the Mediterranean. At the same time, northern European artefact types reached eastern Great Britain in large quantities from across the North Sea. Within this context, the climate became considerably wetter forcing the Bronze Age farmsteads which had grown on lowland areas to relocate to upland sites. 
Defensive structures dating from this time are often impressive, for example the brochs of northern Scotland and the hill forts that dotted the rest of the islands. Examples of hill forts include Maiden Castle, Dorset and Danebury in Hampshire. Hill forts first appeared in Wessex between 550 and 400 BC and often connected with the earlier enclosures attached to the long ditch systems. Danebury appears to have been used for domestic purposes with examples of food storage, industry and occupation being found within their earthworks. The presence of hill forts is possibly because of greater tension between better structured groups, although there are suggestions that in the latter phases of the Iron Age they existed simply to indicate wealth. Alternatively, they may have served as wider centres used for markets and social contact. Population estimates vary but the number of people in Iron Age Great Britain could have been three or four million by 150 BC with most concentrated densely in the agricultural lands of the south. Settlement density and a land shortage may have contributed to rising tensions during the period. The British Iron Age lasted from the first significant use of iron for tools and weapons in Britain to the Romanisation of the southern half of the island after 43 AD. Rome’s influence over northern Britain and Wales was limited and the vestiges of Celtic culture and language remained and Celtic may have been spoken in Wales as late at 700 AD. Although Rome sought to conquer the whole of Britain, the building of the defensive walls by Hadrian and Antonius Pius marked the limits of the Roman world and to their north the Celtic peoples retained their independence Ireland too remained beyond the influence of Rome and its Iron Age only ended by the rise of Christianity.
 Wright, Neil, The Historia Regum Britannie of Geoffrey of Monmouth, (Boydell and Brewer), 1984.
 Lebor Gabála Érenn, original text edited and translated by R. A. Stewart Macalister, 5 Vols. (Irish Texts Society), 1938-1956, and Carey, John. A new introduction to Lebor Gabála Érenn: The Book of the taking of Ireland, edited and translated by R.A. Stewart Macalister, (Irish Texts Society), 1993.
 Looking at insect and plant fossils found with the artifacts, researchers determined that the species dated back to the Early Pleistocence period, between 990,000 and 780,000 years ago. The researchers also tested sediment around the tools and established that they were buried when the Earth’s magnetic field was flipped. The last time this happened was also about 780,000 years ago. See, Parfitt, Simon A., Ashton, Nick M., et al, ‘Early Pleistocene human occupation at the edge of the boreal zone in northwest Europe’, Nature, 466, (8 July 2010), pp. 229-233 and http://www.britishmuseum.org/research/research_projects/featured_project_happisburgh.aspx
 Pryor, Francis, Britain BC: Life in Britain and Ireland before the Romans, (Harper-Collins), 2003.
 Pearson, Michael, Bronze Age Britain, revised edition, (Batsford), 2005, provides a good summary of developments.
 Drews, Robert, The End of the Bronze Age: Changes in Warfare and the Catastrophe of ca. 1200 B.C., (Princeton University Press), 1995, and Miles, Richard, Ancient World: The Search for the Origins of Western Civilisation, (Allen Lane), 2010, pp. 47-57.
 Cunliffe, Barry W., Iron Age Communities in Britain, Fourth Edition: An Account of England, Scotland and Wales from the Seventh Century BC Until the Roman Conquest, (Routledge), 2005.