Imagine that this is your daily life: While on your way to work or on an errand, every 100 meters you pass a police blockhouse. Video cameras on street corners and lamp posts recognize your face and track your movements. At multiple checkpoints, police officers scan your ID card, your irises and the contents of your phone. At the supermarket or the bank, you are scanned again, your bags are X-rayed and an officer runs a wand over your body — at least if you are from the wrong ethnic group. Members of the main group are usually waved through.

You have had to complete a survey about your ethnicity, your religious practices and your “cultural level”; about whether you have a passport, relatives or acquaintances abroad, and whether you know anyone who has ever been arrested or is a member of what the state calls a “special population.”

This personal information, along with your biometric data, resides in a database tied to your ID number. The system crunches all of this into a composite score that ranks you as “safe,” “normal” or “unsafe.”Based on those categories, you may or may not be allowed to visit a museum, pass through certain neighborhoods, go to the mall, check into a hotel, rent an apartment, apply for a job or buy a train ticket. Or you may be detained to undergo re-education, like many thousands of other people.

A science-fiction dystopia? No. This is life in northwestern China today if you are Uighur.

China may no longer be the bleak land of Mao suits, self-criticism sessions and loudspeakers blaring communist slogans. It boasts gleaming bullet trains, luxury malls and cellphone-facilitated consumer life. But when it comes to indigenous Uighurs in the vast western region of Xinjiang, the Chinese Communist Party (C.C.P.) has updated its old totalitarian methods with cutting-edge technology.