The annual growth rate of immigration has been steepest in the developing countries, and about half of all international migration takes place within the developing countries. So far as the involuntary migration (refugees) in concerned, it was about 18 million in 1993 which has fallen to 14 million in 1996. However, the number of refugees is overshadowed by the increase in the number of internally displaced persons those who have been forced to flee their homes by armed conflict, persecution, or natural or man-made disaster, but who remain within their national borders. Because of the rising number of civil wars and local conflicts, the number of internally displaced persons now totals an estimated 30 million worldwide, mostly concentrated in 35 countries.
Africa is the worst affected region, with up to 16 million people having been internally displaced. Several million Muslims migrated from Kosovo (Yugoslavia) to Albania and Macedonia in 1999, because of persecution. About 4 million Afghans took shelter in Pakistan, Iran, Tajikistan and Uzbekistan during the period between 1996 and 2010. Environmental degradation and resource scarcity can help to trigger mass migration. Population growth, land scarcity, and cycle of droughts and floods has encouraged the illegal immigration of more than 10 million Bengalis perhaps 20 million including their descendants to neighbouring Indian states of Assam, Tripura and West Bengal.
The influx has prompted local resentments in N.E. India, especially in Assam, and more than 4,000 people were killed in a series of violent clashes in the early 1980s. Tension continues today. Many governments increasingly view immigration as a problem, despite the fact that immigrant labour often benefits both the home and host countries. Perception of national identity, cultural differences, and fears of unemployment are all contributing to actual and potential hostilities between immigrants and nationals. Nonetheless, immigration, either legal or illegal, seems certain to continue.