The history of humanity is a history of migration, according to Harzig and Hoerder (2009). They continue to emphasize that there was no "prehistory" of unstable and illiterate peoples followed by the "proper history" of settled empires or nations. Periodization differs between macro and micro cultural regions, but Harzig and Hoerder (2009) generalize eight distinct eras of migration over time: Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get the original essay Migration of Homo sapiens out of East Africa around the world Migrations in the era of early sedentary agriculture, 15,000 to 5,000 BC Differentiation of migrations during urbanization in Mesopotamia, Egypt, Indian and East Asian societies and the Mediterranean Phoenician-Hellenistic-Roman worldMigrations from 500 BCE to 1500 CEMigration, intercultural contacts and trade circuits in macro-regions of the world, 1400-1600Dialectic of migrations in colonized and colonized societies, 1600 – 1800,7. Global migration systems of the 19th century Migrations of the 20th and 21st centuries. As Massey (1990) argues, the factors that influence the onset of migration may be very different from the conditions that cause migration to continue, that is, to be perpetuated. After an initial phase of pioneer migration, migration becomes more common in the community, with more and more people imitating current migrants and being helped by them until the migration becomes self-sustaining. There are different aspects of migration perpetuation, including social capital, social networks, migration institutions, and cumulative and circular migration. Rubenstein (2014) states that people decide to migrate due to push factors and pull factors. A push factor encourages people to leave their current location, while a pull factor encourages people to move to a new location. Since for most people, migration is a major step that is not taken lightly, push and pull factors usually play a role. When migrating, people view their current place of residence so negatively that they feel repulsed, and they see another place so attractively that they feel drawn to it. He goes on to argue that three main types of push and pull factors can be identified: economic, cultural and environmental. Economic migration Economic migration is defined as a choice to act to improve the standard of living by obtaining a better paid job. A recent example is when Poland and seven other Eastern European countries joined the EU in 2004, the UK received many economic migrants. In 2009, there were 500,000 workers from Eastern Europe. Pull factors included salaries five times what they could get at home. Some come for seasonal jobs, such as picking vegetables and fruits. More skilled migrants may seek jobs in the medical or educational fields. The economic effects of migration vary considerably. Sending countries may experience both short-term gains and losses, but they may benefit in the long term. For host countries, temporary worker programs help address skills shortages, but can lower domestic wages and increase the welfare burden. The economic effects of migration, both for countries of origin and for receiving countries, can also..