In a world where access to transportation has widened horizons, human migration in search for work, food, housing, freedom from oppression or a better quality of life have radically affected population patterns across the world. Whether due to economic pressure, conflict, persecution, exhaustion of subsistence agricultural land, climate change, or a combination of these and perhaps other factors, there has been massive population movement over the earth's surface in the last half century; and the scale of mass migrations is increasing. The UN Fund for Population Activities noted that the two least desirable features of this mass movement are (a) migration of ill-equipped persons to countries ill equipped to receive them and (b) the drain of qualified personnel from countries that can ill afford to lose them.
People who migrate carry with them the health problems of their place of origin, and often are at high risk of new problems at their destination or at staging points along the way, especially refugee communities. Social tensions are created between newcomers and the existing population. The homelands lose valuable resources. Migration from poor areas to wealthier one increases patterns of inequality whether it is the brain drain from the south to the north, the migration of Asians from east Africa or the movement of desert nomads into squatter camps.
It is currently estimated by the United Nations that the actual number of emigrants in the world at 100 million, namely about 2% of the world population. It is expected that this figure could triple by the year 2000.
Apart from the initial dispersion from India about a thousand years ago (which also occurred in waves), there have been a few other great migrations, or diaspora, in the Gypsy history. Second great migration, known as the Aresajipe, was from south-west Asia into Europe in the 14th century. Third migration was from Europe to the Americas in the 19th and early 20th centuries after the abolition of Romany slavery in Europe in 1856-1864. Another migration wave came in the 60s, when many Gypsies emigrated from late Yugoslavia and Romania to Germany and the U.S.A. Future history might prove that another great migration started in the 1990s, following the fall of the Iron Curtain in Eastern Europe and after the Balkan wars.
The developed countries and their populations tend to see the problem of the gap between the rich countries and poor countries only in terms of the migrants arriving at their borders in thousands and millions each day. Within the third world, millions of people are moving from somewhat poorer to somewhat richer countries—more than 2 million per year in Asia alone. In addition, there are 23 million refugees in the world. overall, about 100 million live outside of the country where they were born.