It's dusty, sweltering, crowded. Waves of people start to arrive.

Some have suitcases. Many, just the clothes on their backs. There are some walking alone, others in groups or with their families.

Nearly all look exhausted, bewildered, worried.

We're at Islam Qala in Afghanistan, on the border with Iran. The people we're seeing crossing over are some of the 1.3 million Afghans who Iran has deported this year.

Many left their homeland for economic survival. Now they're being forced back to where they started, full of anxiety and some, with stories of violent arrests.

Rohullah Mohammadi stands out. He's wearing a smart blue suit and loafers. He has a youthful but serious face. He looks ready for a business meeting, not a sandy border crossing.

He went to Iran to build a better life and earn money to send back to his struggling family. But like many we meet, he crossed illegally, living undocumented in Iran until the police caught up with him.

"They took everything I had and sent me back to Afghanistan," he says.

"They even beat me. They injured my ear. Is this how Islam is supposed to be practised?"

At its peak, as many as 28,000 people have come through this border crossing in just a single day.

Some manage to stay for a day or two, helped by the UN alongside the Taliban authorities.

But the pressure of returning to the difficult life you left, and working out how you'll survive going forward, quickly hits people.

'Never paid'

In a tent for families, we meet Fatimah. She says she took her children to Iran to escape poverty.

"My two daughters worked from six in the morning until 8.30 at night," she recalls, wiping tears from her eyes.

"But they were never paid. The Iranians didn't give them any money."

'16 days beaten in detention'

Lots of children we meet are alone. They all say they were smuggled into Iran, taking on debt owed to the traffickers.

At just 15, baby-faced Tahir says he's the breadwinner for his six siblings and two parents.

He tells us he's just spent 16 days being beaten in a detention centre. And yet he is already feeling compelled to return to Iran - feeling the weight of responsibility for his family.

"I love my homeland Afghanistan deeply and I am even ready to sacrifice my life for it," he says.

"But if there is no work here, how can I survive? I have a family, and they have expectations of me. I must work."

In a room close by, we meet 15 others like him. A whole room of unaccompanied boys who have crossed the border.

The UN is moving them to the nearby city of Herat, where they will stay for a night before being reunited with their families across Afghanistan.

We join them on the journey. Most are strangers to each other.

'Kicked on concrete floor'

For Tahir, it's a soft landing, but a hard adjustment. He looks disorientated as he watches some of the others play football.

He says he can't stop thinking about the brutal detention centre he's just left.

"They would force us to lie down on the concrete floor and kick us," he says.

"In the detention rooms, if someone spoke up they would be forced to lie on the ground. If they protested, they would be sent to a dark solitary cell."

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What is shocking to learn is that nearly every single one of the boys we met says they were smuggled to Iran by traffickers - and nearly every single one says they were beaten in detention.

But Tahir is already making plans to return to Iran. He doesn't think he has a choice.

"I would rather kill myself than see my father begging for money for his hungry children," he says. "I couldn't bear it."

Tahir is one of millions caught up in Iran's crackdown on illegal immigrants. Authorities there set a deadline in September for all undocumented Afghans to leave.

But human rights groups say those living legally in Iran have also been swept up in deportations, and that the numbers crossing have pushed Afghanistan to breaking point.

The country is also being squeezed on its eastern border - Pakistan too has deported tens of thousands of Afghans this year.

We asked the Iranian government about the allegations made by the Afghans we met, including Tahir, but it did not respond to our request for comment.

Girls fleeing Taliban restrictions

Other expelled Afghans we meet fled for an education - girls who were no longer able to attend secondary schools in Afghanistan.

We speak to one mother recently forced to return - struggling with the fact she's now back.

"Every day brought a new restriction, a new policy aimed at preventing women from working," she says.

"There was the compulsory niqab, and also limitations on education for women and girls."

She seems overwhelmed. "When you see the future of your daughter, of your children, slipping away day by day, it's devastating," she adds.

Her daughter tells me she used to love reciting poetry. But when the Taliban returned to her city, she was forced to stop.

Bittersweet family reunion

Tahir hasn't seen his family for two years, and it's a bittersweet return.

His siblings rush out of the house to greet him. His mother cries as she embraces him.

The living room is packed with the siblings he's been financially supporting. They're a wonderful, kind and close family.

His mother Gulghoty sobs as she explains why she had to let him go and likely will again.

"Life here was very hard for him," she says.

"We have a delivery cart but with that alone he could not pay for himself and take care of me. He needs a stable life and a future."

Tahir says, with sobering pragmatism, that he must go back to Iran and "endure the oppression" to save his family.

It's a dynamic playing out across Afghanistan. Huge burdens on young shoulders and a country unable to share the load.

(c) Sky News 2025: 'Beaten for 16 days': Deported Afghans describe brutal treatment by Iran - yet are desperate