Afghan diaspora or Afghan immigrants are citizens of Afghanistan who have emigrated to other countries, or people of Afghan origin who are born outside Afghanistan. Traditionally the borders in between Afghanistan and it's southern and eastern neighbouring state have been fluid and vague. Like many nations created by European empires the borders often do not follow ethnic divisions and many ethnic groups and tribes native to Afghanistan are found on both sides of Afghanistan's present day northern and especially southern borders. This meant that historically there was much movement across present day barriers.
But ever since the Soviet invasion of Afghanistan refugees have fled into the surrounding states. After the Soviets left, civil war, Taliban conquest and most recently the Western-led invasion have meant constant warfare in Afghanistan. Millions have fled the violence, then in times of relative peace returned only to flee again when renewed fighting broke out. About six million Afghan refugees have fled to neighboring Pakistan (mainly NWFP) and Iran, making Afghanistan the largest refugee-producing country in the world, a title it has held for 32 years. 95% of Afghan refugees are located in either Iran or Pakistan. Some NATO countries that were part of the NATO forces took in refugees or Afghans that worked with their respective forces. Ethnic minorities, like Afghan Sikhs and Hindus, often fled to India.
In 2013, more than 2.8 million Afghan refugees were living in Iran with only 0.8 million of them being registered as legal migrants and rest living as illegal refugees in Iran. Similarly 1.5 million officially registered Afghan refugees were reported to be living in Pakistan in addition to approximately one million more illegal refugees.
As shown in the table below, the refugees (both legal and illegal) fled Afghanistan in four main waves: