Kairat Samarkhan looks taciturn and aloof. Or maybe he is just tired after a long day at work. Once he attempted to kill himself by smashing his head against the wall. "I could not stand it anymore," he said.

Samarkhan is talking about his "imprisonment" at a "reeducation camp" in the western Chinese region of Xinjiang. International organizations say over a million people are forced to live in these camps.

According to Human Rights Watch (HRW), a New York-based rights watchdog, human rights violations on this scale have not taken place in China since the Cultural Revolution.

Many "reeducation camps" are spread across the region, which is populated by the Muslim minorities of Uighurs and Kazakhs.

Read more: UN panel 'alarmed' by reports over Xinjiang

'Nobody believes us'

Dozens of people gather at Atajurt, a non-governmental organization in the Kazakh metropolis of Almaty. Many of these people carry photographs and identification documents of their relatives, who have been allegedly arrested by Chinese authorities in Xinjiang. A team of Amnesty International activists records their accounts.

Atajurt was founded in 2017 when the first reports of Kazakh arrests reached the Central Asian country.

"When we made the first cases public, nobody believed us," said Kidirali Orazuly, the founder of Atajurt.

Kazakhstan has close ties to Xinjiang – about 1.6 million ethnic Kazakhs live in the region. About 200,000 Kazakhs from Xinjiang have been naturalized in Kazakhstan since the former Soviet republic gained independence in 1991. Many of these people still have family members in China, therefore when they hear about the disappearance of a relative; they report it to Kazakh authorities.

At the Atajurt office, a woman holds up two large photos of her son and daughter. She said her son was arrested while taking a selfie with a Kazakh pop star on the Chinese side of the border.

Chinese authorities accused her son of being a "double-faced" person, by which they mean someone who is not loyal to the Chinese nation and the ruling Communist Party of China but to their own ethnic group.

To punish the family more, Chinese officials demanded that the woman's daughter return to China and study at a school there.

"I had no choice," the woman said. "They threatened to arrest all my relatives in Xinjiang."

The girl later disappeared into the "reeducation camp," said the woman.

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The man with 'two faces'

Authorities also handed down a verdict of "double-face" to Kairat Samarkhan, who has lived in Kazakhstan since 2009.  When he returned to China to take care of some business matters, the police interrogated him.

They wanted to know what he had been doing in Kazakhstan and whom he had met there. Then they looked through his smartphone. On one of his social media profile pictures he had the initials "KZ," the international abbreviation for Kazakhstan. This sealed the verdict for Samarkhan.

"When I arrived at the camp I thought, now it's all over," he said. "The days in the camp begin with singing the national anthem and afterward 'lessons' are started," he continued, adding that he estimates at least 5,700 prisoners were being held in the camp.

The prisoners had to sing songs praising the Communist Party for hours on end with titles like, "Without the Communist Party there would be no new China" or "The East is red."

They sat through lectures on last year's 19th Party Congress and were required to repeat slogans.

"We learned was a great person Xi Jinping is, and why China is such an amazing place to live," said Samarkhan.

All prisoners were divided in groups according to the reasons behind their incarceration. Those held for religious reasons were in one building, those with foreign contacts in another. There is no legal foundation for this mass incarceration, much less a basis for sentencing. The camp bosses decide with impunity who is freed and who isn't.

"That was the worst part," said Samarkhan. "You don't know how long you are going to be held, if you will ever be freed or if, in the end, they will maybe just execute everyone."

He started to think frequently think about suicide, but any articles of clothing suitable for hanging himself had been taken away. Then he began to slam his head against the wall until he was unconscious. After this, he was released.

Samarkhan's story cannot be verified, but what he describes corresponds to what other prisoners have shared. Suicide attempts come up again and again in reports.

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Protests turn to terrorism?

Xinjiang has long been a conflict-plagued region in China. The Uighurs, the region's largest ethnic group,  have repeatedly rebelled against Chinese rule – sometimes using force.

In 2009, an uprising in the regional capital Urumqi cost around 200 people their lives. In 2014, Uighur separatists carried out a knife and machete attack at a train station in the southern Chinese city of Kunming that killed 29.

China considers the violence to be in line with Islamist attacks in the West.

On the sidelines of a UN Human Rights Committee meeting in September, a Chinese official said the camp system was "necessary to fight religious extremism."

"Maybe it's the necessary way to deal with Islamic or religious extremism, because the West has failed in doing so," said the official.

It was the first time that China had admitted to mass-internment, even if the representative insisted that they weren't camps, but rather "professional training and educational centers."

'Brainwashing' centers

China doesn't seem to be distinguishing between Jihadist ideology and those striving for cultural independence.

"The root of terrorism is ethnic separatism and its ideology is religious extremism," said Xi Jinping.

Since then, the possession of a prayer rug can raise suspicion against Muslims, just like neglecting to raise the Chinese flag, which is now mandatory for residents in many parts of Xinjiang.

"This is brainwashing. They are supposed to feel like part of the Chinese nation and set aside their own ethnic identity," Patrick Poon, a China expert at Amnesty International, told DW.

Kairat Samarkhan is one of the few who have managed to leave China. He is also one of very few former prisoners who is willing to be quoted using his full name. Samarkhan is an orphan, and he has no fear that revenge will be taken on his relatives. Kazakh authorities have warned him about the long arm of the Chinese law and that his statements could get him into trouble.

"But if we don't talk about what is going on there, who else is going to do it?" he said.

Read more: Chinese authorities detain relatives of Radio Free Asia's Uighur reporters