For more than three decades, conflict has forced millions of Afghans to seek refuge abroad.
The biggest exodus occurred during the 10 year Soviet occupation of Afghanistan. By 1989, when Soviet forces withdrew, more than 6 million Afghan refugees were living in neighbouring Pakistan and Iran.
Others fled further afield - to Europe or the United States.
The UN refugee agency, UNHCR, says more than 5.7 million Afghans have returned home since the fall of the Taliban in 2001. But Afghans remain one of the biggest single refugee populations in the world.
Pakistan continues to play host to at least 1.7 million Afghan refugees, with at least another 1 million in Iran.
Meanwhile, in Afghanistan itself, the return of such huge numbers of people has put a huge strain on infrastructure and services. UNHCR estimates that the returnees have increased Afghanistan's population by around 25 per cent. A 2011 survey by the agency showed that more than 40 per cent of returnees in both urban and rural areas had not re-integrated into their home communities.
Meanwhile rising insecurity is continuing to fuel internal displacement: more than 100,000 Afghans fled their homes in the first part of 2011 alone, bringing the overall number of internally displaced to more than 500,000 people.
UNHCR says there are over 1.3 million people "of concern" to it within Afghanistan, including returning refugees, internally displaced people, refugees and asylum seekers.
On UNHCR's Storytelling YouTube channel:
- The harrowing tale of a mother and son who fled the Taliban and now live a meagre existence in Pakistan. Click here to see the video.
- Afghan activist Selay Ghaffar's family were refugees during the time of the Soviet invasion of Afghanistan. Click here to see the video.