Islam Qala: At Zero Point, the main border crossing between Afghanistan and Iran, hundreds of Afghan labourers return to their homeland each day.
Some are exhausted by gruelling working conditions, but many others bear the hallmarks of heroin addiction they acquired while in Iran.
Under the watchful eyes of customs officials from both countries, the labourers cross the windy and arid plains at Islam Qala, the entry point to Herat province and western Afghanistan, after months or years spent working in Iran. Every day, between 1,000 and 1,500 illegal Afghan migrants, mainly young men, return to their country, either voluntarily or -- in around a third of cases -- because they have been expelled.
Iran, which shares a long border with Afghanistan, began taking in millions of Afghan refugees in the 1980s as they fled a war that began with the Soviet invasion and has continued to this day.
The flow of people began to reverse following the fall of the Taliban regime at the end of 2001, with millions of Afghans choosing to return home.
And the pace has picked up in the past few years due to an increasingly repressive environment for Afghan refugees in Iran, particularly the 1.7 million who are unregistered (a further 840,000 are legal).
Situated 120 kilometres from the border, Herat, the main city in Afghanistan's west, welcomes the majority of those who have come back.
But authorities have witnessed a disturbing trend: many of the returnees are addicted to drugs they first tried out while in Iran.
In an ironic twist, most of the drugs consumed are exported from Afghanistan, which produces 85 percent of the world's opium, later refined into heroin.
A large portion of Afghanistan's drugs are transported to the rest of the world via Iran. According to Mohammed Reza Stanikzai, a senior narcotics official at the UNODC, initial research also backs the claim that “most (Afghan) drug users started their first drug use outside the country”.AFP
