WHEN REPORTS began filtering out of China last year about a massive indoctrination and internment drive against ethnic Muslim Uighurs in the western region of Xinjiang, the government in Beijing denied that anything was going on. Later, China acknowledged that criminals and people who committed minor offenses might be sent to “vocational education” centers there. Now, the regime has gone a step further, revising a regional law to admit the dark reality: An archipelago of concentration camps has been built.

China has long used harsh penal systems for dissidents and political prisoners. One branch, known as “laojiao,” or “reeducation through labor,” existed outside the regular prison system. People were sent to reeducation by public security agencies without trial or legal procedure; it was widely used for dissidents and petty criminals, according to Adrian Zenz, a lecturer in social research methods at the European School of Culture and Theology, in Korntal, Germany. In 2013, China’s government wisely closed down this system, seeing it as a relic of the past. At the time, Mr. Zenz estimates, it had 350 facilities with about 160,000 people.

Then, in 2017, China began rapidly erecting a “reeducation” system aimed at the restive Uighur population and other Muslim minorities, including Kazakhs. Like the earlier version, the new incarceration system was to be extrajudicial: no due process, no rule of law. According to Mr. Zenz, who has studied it, the scale is huge; there are now more than 1 million Uighurs and others incarcerated, or 11.5 percent of the Uighur population of Xinjiang between ages 20 and 79. There may be as many as 1,200 facilities. In a recent talk at Harvard University’s Fairbank Center for Chinese Studies, Mr. Zenz described them as bleak, with hardened floors, watchtowers, no trees, high fences and endless hours of “reeducation” to make the Uighurs think like the majority Han Chinese. He pointed out that the intent is not to kill people but to kill the memory of who they are, to wipe out their separate identity, language and history. Even the slightest perceived infraction, such as having a copy of the Koran on a phone or making a contact abroad, can result in incarceration, he said.