migration, of people, geographical movements of individuals or groups for the purpose of permanently resettling.

Early History

Migrations have occurred throughout history and have played an important part in the peopling of all the areas of the earth. Primitive migrations were usually in search of food, but could also result from physical changes, such as the advance of the continental ice sheets, and invasion by other peoples. The most important migrations in European history were the Gothic invasions (3d–6th cent.; see Germans Germans, great ethnic complex of ancient Europe, a basic stock in the composition of the modern peoples of Sweden, Norway, Denmark, Iceland, Germany, Austria, Switzerland, N Italy, the Netherlands, Belgium, Luxembourg, N and central France, Lowland Scotland, and
..... Click the link for more information. ), the Arab invasions (7th–8th cent.; see Arabs Arabs, name originally applied to the Semitic peoples of the Arabian Peninsula. It now refers to those persons whose primary language is Arabic. They constitute most of the population of Algeria, Bahrain, Egypt, Iraq, Jordan, Kuwait, Lebanon, Libya, Morocco, Oman,
..... Click the link for more information. ), the westward migration of the Golden Horde of Jenghiz Khan Jenghiz Khan (jĕng`gĭz, –gĭs kän) or Genghis Khan
..... Click the link for more information. (13th cent.), and the invasions of the Ottoman Turks (14th–16th cent.; see Ottoman Empire Ottoman Empire (ŏt`əmən), vast state founded in the late 13th cent.
..... Click the link for more information. ; Turks Turks, term applied in its wider meaning to the Turkic-speaking peoples of Turkey, Russia, Central Asia, Xinjiang in China (Chinese Turkistan), Azerbaijan and the Caucasus, Iran, and Afghanistan.
..... Click the link for more information. ).

Later Migrations

From the 17th to the 20th cent. migration involved individuals and families rather than nations or mass groups. The basic motive was economic pressure, as areas of low population density attracted people from high-density areas where economic opportunity was low. The desire for religious and political freedom has also been important, and national policies have played a part. In the largest international migration in history, c.65 million people migrated from Europe to North America and South America between the 17th cent. and World War II, while another 17 million went to Africa and Australia.

Nearly 12 million people, most from Mexico or Asia, migrated to the United States in the 1970s and 80s. Within the United States, migration patterns have traditionally been from east to west. Migration from north to south since the 1960s has resulted in the ascendancy of the Sun Belt Sun Belt or Sunbelt, southern tier of the United States, focused on Florida, Texas, Arizona, and California, and extending as far north as Virginia.
..... Click the link for more information. , a region extending from Florida to S California. This trend has been supported by the southward migration of many blacks. Government regulation of migration became significant in the 20th cent. (see immigration immigration, entrance of a person (an alien ) into a new country for the purpose of establishing permanent residence. Motives for immigration, like those for migration generally, are often economic, although religious or political factors may be very important.
..... Click the link for more information. ).

Modern Migration Trends

Normal internal migration has been characterized by a population shift from rural to urban areas. In the United States, the portion of the population that lives in urban areas has risen steadily from 30% in 1910 to more than 70% in 1990; in Brazil, the percentage of urban dwellers has risen from 30% to 75% since 1940. Within urban areas, a large population shift from central cities to suburbs has occurred in the last half of the 20th cent. The development of totalitarianism and World War II resulted in a new pattern of forced mass migration within Europe. Over 30 million people were forcibly moved or scattered by the Nazis. In the postwar period c.10 million Germans and persons of German descent were forcibly expelled from Eastern Europe.

Other forced migrations since World War II have included the partitioning of India and Pakistan, which uprooted 18 million, and the establishment of the state of Israel, which created about one million refugees (see refugee refugee, one who leaves one's native land either because of expulsion or to escape persecution. The legal problem of accepting refugees is discussed under asylum ; this article considers only mass dislocations and the organizations that help refugees.
..... Click the link for more information. ). After the fall of Saigon (now Ho Chi Minh City) at the end of the Vietnam War Vietnam War, conflict in Southeast Asia, primarily fought in South Vietnam between government forces aided by the United States and guerrilla forces aided by North Vietnam.
..... Click the link for more information. in 1975, more than 600,000 fled Vietnam in the face of political persecution; many fled by boat and became known as the "boat people." In South Africa, under the policies of apartheid apartheid (əpärt`hīt) [Afrik.
..... Click the link for more information. , blacks were forced to live in designated "homelands" from 1959 to 1994. The Soviet invasion of Afghanistan in 1979 led to the migration of millions of Afghans to neighboring Pakistan and Iran.

In the 1980s and 90s war and civil strife continued to force massive refugee migration in many parts of the world. In Somalia and Ethiopia, civil war combined with long-term drought have resulted in large migrations of peoples (often from rural to urban areas and to neighboring countries) in an attempt to avoid famine. Hundreds of thousands of Kurdish refugees (see Kurds Kurdistan, an extensive plateau and mountain area, c.74,000 sq mi (191,660 sq km), in SW Asia, including parts of E Turkey, NE Iraq, and NW Iran and smaller sections of NE Syria and Armenia. The region lies astride the Zagros Mts. (Iran) and the eastern extension of the Taurus Mts.
..... Click the link for more information. ) have migrated from Iraq to Turkey and Iran in the wake of the civil war that followed the Persian Gulf War First Persian Gulf War, Jan.–Feb., 1991, was an armed conflict between Iraq and a coalition of 32 nations including the United States, Britain, Egypt, France, and Saudi Arabia. It was a result of Iraq's invasion of Kuwait on Aug.
..... Click the link for more information. in 1991. The disintegration of Yugoslavia in the 1990s caused the dislocation of many peoples, especially Bosniaks, Croats, Serbs in areas other than Serbia, and Kosovars. In Rwanda and Burundi, millions of people, primarily Hutus, fled as ethnic civil war wrenched those nations in the mid-1990s; many of them fled to Zaïre (now Congo), where their presence aggravated civil and international strife.

Bibliography

See A. A. Brown and E. Neuberger, Internal Migration (1977); M. Greenwood, Migration and Economic Growth in the United States (1981); G. J. Lewis, Human Migration (1982); W. Weidlich and G. Haag, ed., Interregional Migration (1988).

migration

(1) A change from one hardware or software technology to another. Migration is a way of life in the computer industry. For example, once known only to those in the glass-enclosed datacenter, users today understand the meaning of migrating from one operating system to another.

(2) Moving data from one storage system to another (data migration). See HSM.

(3) Moving data and applications from one computer to another. See PC migration.

migration [mī′grā·shən]

(chemistry)

The movement of an atom or group of atoms to new positions during the course of a molecular rearrangement.

(chemical engineering)

bleeding

(computer science)

Movement of frequently used data items to more accessible storage locations, and of infrequently used data items to less accessible locations.

(genetics)

The transfer of genetic information among populations by the movement of individuals or groups of individuals from one population into another.

(geology)

Movement of a topographic feature from one place to another, especially movement of a dune by wind action.

Movement of liquid or gaseous hydrocarbons from their source into reservoir rocks.

(hydrology)

Slow, downstream movement of a system of meanders.

(metallurgy)

The uncontrolled movement of certain metals, particularly silver, from one location to another, usually with associated undesirable effects such as oxidation or corrosion.

(solid-state physics)

The movement of charges through a semiconductor material by diffusion or drift of charge carriers or ionized atoms.

The movement of crystal defects through a semiconductor crystal under the influence of high temperature, strain, or a continuously applied electric field.

(vertebrate zoology)

Periodic movement of animals to new areas or habitats.