Pre-historical migration of human populations began with the movement of Homo erectus out of Africa across Eurasia about a million years ago. Homo sapiens appears to have colonized all of Africa about 150 millennia ago, moved out of Africa some 80 millennia ago, and spread across Eurasia and to Australia before 40 millennia ago. Migration to the Americas took place about 20 to 15 millennia ago, and by 1 millennium ago, all the Pacific Islands were colonized. Later population movements notably include the Neolithic revolution and Indo-European expansion, part of which emerges in the earliest historic records.
Before the modern era, migrations are often confusing in the written record because the history is written by societies on the periphery of the migrating peoples, or by their descendants who have given up the nomadic way of life. This is true of the era that follows the collapse of classical civilization in Europe, including the Early Medieval Great Migrations, and the related Turkic expansion. Much better understood are the Age of Exploration and European Colonialism, which led to an accelerated pace of migration over vast distances as new means of transportation emerged.
Early migrations 
Evolution of the genus Homo took place in Africa. First Homo erectus migrated out of Africa across Eurasia, beginning about one million years ago, no doubt using some of the same available land routes north of the Himalayas that were later to become the Silk Road, and across the Strait of Gibraltar. Bruce Bower has suggested that Homo erectus may have built rafts and sailed oceans, a theory that has raised some controversy.
The expansion of Homo erectus was followed by that of Homo sapiens. The matrilinear most recent common ancestor shared by all living human beings, dubbed Mitochondrial Eve, probably lived roughly 150-120 millennia ago, the time of Homo sapiens idaltu, probably in the area of modern Ethiopia, Kenya or Tanzania. Around 100-80 millennia ago, three main lines of Homo sapiens sapiens diverged, bearers of mitochondrial haplogroup L1 (mtDNA) / A (Y-DNA) colonizing Southern Africa (the ancestors of the Khoisan (Capoid) peoples), bearers of haplogroup L2 (mtDNA) / B (Y-DNA) settling Central and West Africa (the ancestors of Niger–Congo and Nilo-Saharan speaking peoples and of the Mbuti pygmies), while the bearers of haplogroup L3 remained in East Africa. Some 70 millennia ago, a part of the L3 bearers migrated into the Near East, spreading east to southern Asia and Australasia some 60 millennia ago, northwestwards into Europe and eastwards into Central Asia some 40 millennia ago, and further east to the Americas from c. 30 millennia ago.
Neolithic Revolution 
Agriculture is believed to have first been practised some 10,000 years ago in the Fertile Crescent (see Jericho). From there, it propagated as a "wave" across Europe, a view supported by Archaeogenetics, reaching northern Europe some 5 millennia ago. VN
Bantu expansion 
The Bantu first originated around the Benue-Cross rivers area in southeastern Nigeria and spread over Africa to the Zambia area. Sometime in the 2nd millennium BC, perhaps triggered by the drying of the Sahara and pressure from the migration of people from the Sahara into the region, they were forced to expand into the rainforests of central Africa (phase I). In the 1st millennium BC, they began a more rapid second phase of expansion beyond the forests into southern and eastern Africa, and again in the 1st millennium as new agricultural techniques and plants were developed in Zambia. By about 1000, it had reached modern day Zimbabwe and South Africa. In Zimbabwe, a major southern hemisphere empire was established, with its capital at Great Zimbabwe. By the 14th or 15th century, the Empire had surpassed its resources and had collapsed.
The islands of the Pacific were the last region on Earth to be populated by humans, as recently as twelve to fifteen centuries ago.
With the art of open-sea navigation involving the most confident and courageous use of the available technologies of boat-building, combined with the most sophisticated understanding of currents and prevailing winds, the Polynesians, starting with the Lapita culture, have proven to be the most successful in the art of navigation, if the permanent spread of culture is taken into account, for the Norse adventurers in the North Atlantic and the Arab traders in the Indian Ocean did not create permanent settlements. The Lapita people, who got their name from the archaeological site in Lapita, New Caledonia, where their characteristic pottery was first discovered, came from Austronesia, probably New Guinea. Their navigation skills took them to the Solomon Islands, around 1600 BC, and later to Fiji, Samoa and Tonga. By the beginning of the 1st millennium BC, most of Polynesia was a loose web of thriving cultures who settled on the islands' coasts and lived off the sea. By 500 BC Micronesia was completely colonized; the last region of Polynesia to be reached was New Zealand in around 1000.
Polynesian migration patterns also have been studied by linguistic analysis, and recently by analyzing characteristic genetic alleles of today's inhabitants. Both methods resulted in supporting the original archaeological findings.
The Americas 
The specifics of Paleo-Indians migration to and throughout the Americas, including the exact dates and routes traveled, are subject to ongoing research and discussion. The traditional theory has been that these early migrants moved into the Beringia land bridge between eastern Siberia and present-day Alaska around 40,000–17,000 years ago, when sea levels were significantly lowered due to the Quaternary glaciation. These people are believed to have followed herds of now-extinct pleistocene megafauna along ice-free corridors that stretched between the Laurentide and Cordilleran ice sheets. Another route proposed is that, either on foot or using primitive boats, they migrated down the Pacific Northwest coast to South America. Evidence of the latter would since have been covered by a sea level rise of hundreds of meters following the last ice age.
Archaeologists contend that Paleo-Indians migration out of Beringia (eastern Alaska), ranges from 40,000 to around 16,500 years ago. This time range is a hot source of debate and will be for years to come. The few agreements achieved to date are the origin from Central Asia, with widespread habitation of the Americas during the end of the last glacial period, or more specifically what is known as the late glacial maximum, around 16,000–13,000 years before present.
The Inuit are the descendants of what anthropologists call the Thule culture, which emerged from western Alaska around 1000 and spread eastward across the Arctic, displacing the Dorset culture (in Inuktitut, the Tuniit). Inuit historically referred to the Tuniit as "giants", or "dwarfs", who were taller and stronger than the Inuit. Researchers hypothesize that the Dorset culture lacked dogs, larger weapons and other technologies used by the expanding Inuit society. By 1300, the Inuit had settled in west Greenland, and finally moved into east Greenland over the following century. The Inuit had trade routes with more southern cultures. Boundary disputes were common and gave rise to aggressive actions. Warfare was common among Inuit groups with sufficient population density. Inuit, such as the Nunatamiut (Uummarmiut) who inhabited the Mackenzie River delta area, often engaged in common warfare. The Central Arctic Inuit lacked the population density to engage in warfare. In the 13th century, the Thule culture began arriving in Greenland from what is now Canada. Norse accounts are scant. Norse-made items from Inuit campsites in Greenland were obtained by either trade or plunder. One account, Ívar Bárðarson, speaks of "small people" with whom the Norsemen fought. 14th-century accounts that a western settlement, one of the two Norse settlements, was taken over by the Skræling.
The Indo-European migration has variously been dated to the end of the Neolithic (Marija Gimbutas: Corded ware, Yamna, Kurgan), the early Neolithic (Colin Renfrew: Starčevo-Körös, Linearbandkeramic) and the late Palaeolithic (Marcel Otte, Paleolithic Continuity Theory).
The speakers of the Proto-Indo-European language are usually believed to have originated to the North of the Black Sea (today Eastern Ukraine and Southern Russia), and from there they gradually migrated into, and spread their language by cultural diffusion to, Anatolia, Europe, and Central Asia Iran and South Asia starting from around the end of the Neolithic period (see Kurgan hypothesis). Other theories, such as that of Colin Renfrew, posit their development much earlier, in Anatolia, and claim that Indo-European languages and culture spread as a result of the agricultural revolution in the early Neolithic.
Relatively little is known about the inhabitants of pre-Indo-European "Old Europe". They are believed to have been garden-plot horticulturalists. The Basque language remains from that era, as do the indigenous languages of the Caucasus. The Sami are genetically distinct among the peoples of Europe, but the Sami languages, as part of the Uralic languages, spread into Europe about the same time as the Indo-European languages. However, since that period speakers of other Uralic languages such as the Finns and the Estonians have had more contact with other Europeans, thus today sharing more genes with them than the Sami.
The earliest migrations we can reconstruct from historical sources are those of the 2nd millennium BC. The Proto-Indo-Iranians began their expansion from c. 2000 BC, the Rigveda documenting the presence of early Indo-Aryans in the Punjab from the late 2nd millennium BC, and Iranian tribes being attested in Assyrian sources as in the Iranian plateau from the 9th century BC. In the Late Bronze Age, the Aegean and Anatolia were overrun by moving populations, summarized as the "Sea Peoples", leading to the collapse of the Hittite Empire and ushering in the Iron Age.
Early Iron Age 
The Dorian invasion of Greece led to the Greek Dark Ages. Very Little is known about the period of the 12th to 9th centuries BC, but there were significant population movements throughout Anatolia and the Iranian plateau. Iranian peoples invaded the territory of modern Iran in this period, taking over the Elamite Empire. The Urartians were displaced by Armenians, and the Cimmerians and the Mushki migrated from the Caucasus into Anatolia. A Thraco-Cimmerian connection links these movements to the Proto-Celtic world of central Europe, leading to the introduction of Iron to Europe and the Celtic expansion to western Europe and the British Isles around 500 BC.
The great migrations 
Western historians refer to the period of migrations that separated Antiquity from the Middle Ages in Europe as the Great Migrations or as the Migrations Period. This period is further divided into two phases.
The first phase, from 300 to 500, saw the movement of Germanic, Sarmatian and Hunnic tribes and ended with the settlement of these peoples in the areas of the former Western Roman Empire. (See also: Ostrogoths, Visigoths, Burgundians, Suebi, Alamanni, Marcomanni).
The second phase, between 500 and 900, saw Slavic, Turkic and other tribes on the move, re-settling in Eastern Europe and gradually making it predominantly Slavic. Moreover, more Germanic tribes migrated within Europe during this period, including the Lombards (to Italy), and the Angles, Saxons, and Jutes (to the British Isles). See also: Avars, Bulgars, Huns, Arabs, Vikings, Varangians. The last phase of the migrations saw the coming of the Hungarians to the Pannonian plain.
German historians of the 19th century referred to these Germanic migrations as the Völkerwanderung, the migrations of the peoples.
The European migration period is connected with the simultaneous Turkic expansion which at first displaced other peoples towards the west, and by High Medieval times, the Seljuk Turks themselves reached the Mediterranean.
Medieval and Early Modern Europe 
The medieval period, although often presented as a time of limited human mobility and slow social change in the history of Europe, in fact saw widespread movement of peoples. The Vikings from Scandinavia raided all over Europe from the 8th century and settled in many places, including Normandy, the north of England, Scotland and Ireland (most of whose urban centres were founded by the Vikings). The Normans later conquered the Saxon Kingdom of England, most of Ireland, southern Italy and Sicily, Iberia was invaded by Muslim Arabs, Berbers and Moors in the 8th century, founding new Kingdoms such as al Andalus and bringing with them a wave of settlers from North Africa.
In the other direction, European Christian armies conquered Palestine for a time during the Crusades 11th to 13th centuries, founding three Christian kingdoms and settling them with Christian Knights and their families. This permanent migration was relatively small however and was one of the reasons why the Crusaders eventually lost the their hold on the Holy Lands.
Massive migrations of Germans took place into East Central and Eastern Europe, reaching its peak in the 12th to 14th centuries. These Ostsiedlung settlements in part followed territorial gains of the Holy Roman Empire, but areas beyond were settled, too.
Internal European migration stepped up in the Early Modern Period. In this period, major migration within Europe included the recruiting by monarchs of landless laborers to settle depopulated or uncultivated regions and a series of forced migration caused by religious persecution. Notable examples of this phenomenon include the expulsion of the Jews from Spain in 1492, mass migration of Protestants from the Spanish Netherlands to the Dutch Republic after the 1580s, the expulsion of the Moriscos from Spain in 1609, and the expulsion of the Huguenots from France in the 1680s. Since the 14th century, the Serbs started leaving the areas of their medieval Kingdom and Empire that was overrun by the Ottoman Turks and migrated to the north, to the lands of today's Vojvodina (northern Serbia), which was ruled by the Kingdom of Hungary at that time. The Habsburg monarchs of Austria encouraged them to settle on their frontier with the Turks and provide military service by granting them free land and religious toleration. The two greatest migrations took place in 1690 and 1737. Other instances of labour recruitments include the Plantations of Ireland - the settling of Ireland with Protestant colonists from England, Scotland and Wales in the period 1560-1690 and the recruitment of Germans by Catherine the Great of Russia to settle the Volga region in the 18th century.
European Colonialism from the 16th to the early 20th centuries led to an imposition of a European colonies in many regions of the world, particularly in the Americas, South Asia, Sub-Saharan Africa and Australia, where European languages remain either prevalent or in frequent use as administrative languages. Major human migration before the 18th century was largely state directed. For instance, Spanish emigration to the New World was limited to settlers from Castile who were intended to act as soldiers or administrators. Mass immigration was not encouraged due to a labour shortage in Europe (of which Spain was the worst affected by a depopulation of its core territories in the 17th century).
Europeans also tended to die of tropical diseases in the New World in this period and for this reason England, France and Spain preferred using slaves as free labor in their American possessions. Many historians attribute a change in this pattern in the 18th century to population increases in Europe.
However, in the less tropical regions of North America's east coast, large numbers of religious dissidents, mostly English Puritans, settled during the early 17th century. Spanish restrictions on emigration to Latin America were revoked and the English colonies in North America also saw a major influx of settlers attracted by cheap or free land, economic opportunity and the continued lure of religious toleration.
A period in which various early English colonies had a significant amount of self-rule prevailed from the time of the Plymouth colony's founding in 1620 through 1676, as the mother country was wracked by revolution and general instability. However, King William III decisively intervened in colonial affairs after 1688 and the English colonies gradually came more directly under royal governance, with a marked effect on the type of emigration. During the early 18th century, significant numbers of non-English seekers of greater religious and political freedom were allowed to settle within the British colonies, including Protestant Palatine Germans displaced by French conquest, French Huguenots disenfranchised by an end of religious tolerance, Scotch-Irish Presbyterians, Quakers who were often Welsh, as well as Presbyterian and Catholic Scottish Highlanders seeking a new start after a series of unsuccessful revolts.
The English colonists who came during this period were increasingly moved by economic necessity. Some colonies, including Georgia, were settled heavily by petty criminals and indentured servants who hoped to pay off their debts. By 1800, European emigration had transformed the demographic character of the American continent. This was also due in part to the devastating effect of European diseases and warfare on Native American populations.
The European settlers' influence elsewhere was less pronounced as in South Asia and Africa, European settlement in this period was limited to thin layer of administrators, traders and soldiers.
Landnahme is a German term, literally translating to "land-taking", used for legendary or mythological and historiographical accounts alike concerning how a given people came to inhabit its present territory. Notable Landnahme events include:
- The conquest of Canaan in the Hebrew Bible, accounting for the arrival of the Israelites in the Promised Land
- The Indo-Aryan migration and expansion within India alluded to in the Rigveda
- The invasion traditions in the Irish Mythological Cycle, accounting for how the Gaels came to Ireland
- The arrival of the Franks in the territories subsequently known as Francia
- The Anglo-Saxon invasion of Britain
- The arrival of the Slavs in the course of the Slavic migrations
- The settlement of Iceland
- The Seljuk invasion of Anatolia
- The Hungarian conquest of Pannonia
Modern migration 
While the pace of migration had accelerated since the 18th century already (including the involuntary slave trade), it would increase further in the 19th century. Manning distinguishes three major types of migration: labour migration, refugee migrations and lastly: urbanization. Millions of agricultural workers left the countryside and moved to the cities causing unprecedented levels of urbanization. This phenomenon began in Britain in the late 18th century and spread around the world and continues to this day in many areas.
Industrialization encouraged migration wherever it appeared. The increasingly global economy globalised the labour market. Atlantic slave trade diminished sharply after 1820, which gave rise to self-bound contract labour migration from Europe and Asia to plantations. Also overpopulation, open agricultural frontiers and rising industrial centres attracted voluntary, encouraged and sometimes coerced migration. Moreover, migration was significantly eased by improved transportation techniques.
During this same period similar large numbers of people migrated over large distances within Asia. Southeastern Asia received 50 million migrants, mainly from India and south China. North Asia, that be Manchuria, Siberia, Central Asia and Japan together, received another 50 million, in a migration that started in the 1890s with migrants from China, Russia and Korea, and was especially large due to coerced migration from the Soviet Union and Japan in the 1930s. Less is known about exact numbers of the migrations from and within Africa in this period, but Africa experienced a small net immigration between 1850 and 1950, from a variety of origins.
Provisions of the Potsdam Agreement from 1945 signed by victorious Western Allies and the Soviet Union led to one of the largest European migrations, and definitely the largest in the 20th century. It involved the migration and resettlement of close to or over 20 million people. The largest affected group were 16.5 million Germans expelled from Eastern Europe westwards. The second largest group were Poles, expelled westwards from eastern Kresy region and resettled in the so-called Recovered Territories (see Oder-Neisse line). Hundreds of thousands of Poles, Ukrainians, Lithuanians, Latvians, Estonians, and some Belarusians, were in the meantime expelled eastwards from Europe to the Soviet Union. Finally, many of the several hundred thousand Jews remaining in the Eastern Europe after the Holocaust migrated outside Europe to Israel and the USA.
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- This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press.