First-of-its-kind courtroom testimony here has corroborated allegations that the Chinese government has built a network of internment camps in western China where Muslim minorities are held without charge for “reeducation.”

Sayragul Sauytbay, an ethnic Kazakh Chinese national, said she crossed from China’s Xinjiang region to Kazakhstan without proper papers after being forced to work at a camp where around 2,500 ethnic Kazakhs were being held for indoctrination.

“In China, they call it a political camp, but really it was a prison in the mountains,” she told a court last month packed with Kazakh villagers, reporters and a few tight-lipped Chinese diplomats.

Interviews by The Washington Post with 20 other people in Kazakhstan familiar with the experiences of ethnic Kazakhs in China, including three former detainees and more than a dozen people who say they believe a family member is in detention, provided similar accounts of the camps, with additional details.