The primary reason for the large scale migration flows among European countries during the twentieth century was; The motivation to reach quotas set by individual countries
Just after the end of second world war, a lot of people migrated from country side to developed countries looking for work that could give them a better life. Thus, a lot of unskilled labors got jobs in developed countries after the world war.
Now, when countries began to face economic crisis, a lot of those migrated workers began going back to their home countries due to land shortage and job shortage as well as farmers facing crop failures.
Other causes of this migration was civil war that took place in Spain, many people migrating to seek religious, political and personal freedom impacted by global conflict.
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