Mass Migration is both a disaster and result of disaster.It uproots many generations,disrupts economy,government, disturbs cultural continuity and many times  causes mass casualty.

Moreover,the place and society receiving the migrants is overburdened.The natural and human resources and drained disastrously.The environment of the receiving place is mostly destroyed .normally,migrants hunt animals for food.Intrude into  forest for food,fuel,herbs,timber and hiding.There are many instances in which whole forest of the host place was destroyed.

Mass migration refers to the migration of large groups of people from one geographical area to another. Mass migration is distinguished from individual or small scale migration; and also from seasonal migration, which may occur on a regular basis.

A specific mass migration that is seen as especially influential to the course of history may be referred to as a ‘great migration’. For example, great migrations include the Barbarian Invasions during the Roman Empire, the Great Migration from England of the 1630s, the California Gold Rush from 1848–1850, the Great Migration of African Americans from the rural American south to the industrial north during 1920–1950, and The Great Oromo Migrations of Oromo tribes during the 15th and 16th centuries in the Horn of Africa. UNHCR estimates 14 million Hindus, Sikhs and Muslims were displaced during the partition of India, the largest mass migration in human history. The largest documented voluntary emigration in history was the Italian diaspora from Italy between 1861 and 1970, with 13 million people leaving the country.

Historians often identify an ‘age of mass migration’ occurring from c. 1850 to 1914 (sometimes 1940), in which long distance migration occurred at an unprecedented and exceptionally high rate.

There were three factors that led to the ‘age of mass migration’. First, cost of migration decreased dramatically. Second, benefits of migration rise (returns on migration was higher in the United States than in other countries). Third, open border regimes. ‘Age of mass migration’ usually refers to the voluntary transatlantic migration of European peasants and labourers to the Americas. Immigration from Europe accounted for about 40% of total United States population growth in the late 19th century. However, it has been argued that the term should include other mass migrations that occurred in the same period, since similar large numbers of people migrated long distances within the continent of Asia, most notably during the Pakistan Movement and subsequent partition of India in 1947. During open border regimes, immigrants attracted by falling costs of migration and higher wages in the U.S. Migrant selection varied over time and across sending country, depending on relative wage premium in U.S. for high/low skilled and cost of migration. In the late 20th century, migrants converge upon native-born in labor market but never fully catch up.

Mass migration may also be forced migration, such as the Atlantic slave trade.

Religious persecution mass migrations, such as the biblical Exodus.

Although some researchers talk about mass migration of Aryan race.It is totally baseless theory propagated by European colonizer to justify their migration to India and other Asian countries.Recent scientific evidences,historical records ,documents,exvation findings and cultural study completely prove that this theory was propagated to justify the loot of Asian wealth and destruction of Asian culture by Europeans.

Similarly, mass migrations may take place in the form of deportation. For example, Japanese internment in the United States and imprisonment in Nazi concentration camps during World War II, deportations to Gulag camps in the Soviet Union, and coolie-labor in Southeast Asia and the Caribbean.Mauritius,Fiji,Trinidad and Tobago etc received these uprooted laborer ,who never returned to India.

On the 15th of August 1947, the partition of British India caused the movement of 18 million people. This caused both religious and civil tensions between Hindus and Muslims. This resulted in the highest casualty rate for one migration according to the Guinness Book of World Records 2014. One million people were killed and 12 million became homeless.

Often a distinction is madebetween voluntary and involuntary migration, or between refugees fleeing political conflict or natural disaster vs. economic or labor migration, but these distinctions are difficult to make and partially subjective, as the motivators for migration are often correlated. The World Bank’s report estimates that, as of 2010, 16.3 million or 7.6% of migrants qualified as refugees. At the end of 2012, approximately 15.4 million people were refugees and persons in refugee-like situations – 87% of them found asylum in developing countries.

Humanitarian Crisis

Humanitarian crisis also cause mass migration.Each humanitarian crisis is caused by different factors and as a result, each different humanitarian crisis requires a unique response targeted towards the specific sectors affected. This can result in either short-term or long-term damage. Humanitarian crises can either be natural disasters, man-made disasters or complex emergencies. In such cases, complex emergencies occur as a result of several factors or events that prevent a large group of people from accessing their fundamental needs, such as food, clean water or safe shelter.

Examples of humanitarian crises include armed conflicts, epidemics, famine, natural disasters and other major emergencies.If such a crisis causes large movements of people it could also become a refugee crisis. For these reasons, humanitarian crises are often interconnected and complex and several national and international agencies play roles in the repercussions of the incidences.