Still, many who have emerged from the indoctrination program say it has hardened public attitudes against Beijing.

“It was of absolutely no use,” said Omurbek Eli, a Kazakh businessman, of his time held in a camp in 2017. “The outcome will be the opposite. They will become even more resistant to Chinese influence.”

For many families, the disappearance of a loved one into the camps can be devastating, both emotionally and economically — a point reflected in reports posted online by the party’s “work teams.”

Some of these reports describe Uighur families unable to harvest crops on their own because so many members have been taken away, and one mentioned a mother left to care for five children. In another report, an official near Hotan described holding a village meeting to calm distraught relatives of those sent to the camps.

The mass internments also break Uighur families by forcing members to disown their kin or by separating small children from their parents. So many parents have been detained in Kashgar, a city in western Xinjiang, that it has expanded boarding schools to take custody of older, “troubled” children.

“Whether consciously or unconsciously, authorities in Xinjiang have recognized the power of families as an alternative source of authority,” said Rian Thum, a professor at Loyola University in New Orleans who has followed the detentions. “The kind of extreme party loyalty they want has no room for that.”

Ms. Gul said the camp she was in was ramshackle enough that children who lived nearby sometimes crept up to a window late at night and called out to their mothers inside. “Their children would come and say, ‘Mother, I miss you,’” she said.

“We didn’t say anything,” she added, “because there was a camera inside the cell.”