It was a compilation of real-time data on more than 2.5 million people in western China, updated constantly with GPS coordinates of their precise whereabouts.
Alongside their names, birthdates and places of employment, there were notes on the places that they had most recently visited mosque, hotel, restaurant.
The discovery by Gevers, a Dutch cybersecurity researcher who revealed it on Twitter last week, has given a rare glimpse into China's extensive surveillance of Xinjiang, a remote region home to an ethnic minority population that is largely Muslim.
The area has been blanketed with police checkpoints and security cameras that apparently are doing more than just recording what happens.
It illustrates how far China has taken facial recognition in ways that would raise alarm about privacy concerns in many other countries and serves as a reminder of how easily technology companies can leave supposedly private records exposed to global snoopers.
Gevers found that SenseNets, a Chinese facial recognition company, had left the database unprotected for months, exposing people's addresses, government ID numbers and more. After Gevers informed SenseNets of the leak, he said, the database became inaccessible.
"This system was open to the entire world, and anyone had full access to the data," said Gevers, noting that a system designed to maintain control over individuals could have been "corrupted by a 12-year-old."
He said it included the coordinates of places where the individuals had recently been spotted by "trackers" likely to be surveillance cameras. The stream indicated that the data is constantly being updated with information on people's whereabouts, he said in an interview over a messaging app.
Gevers posted a graph online showing that 54.9 percent of the individuals in the database were identified as Han Chinese, the country's ethnic majority, while 28.3 percent were Uighur and 8.3 percent were Kazakh, both Muslim ethnic minority groups.
Xinjiang, which borders central Asia in China's far west, has been subject to severe security measures in recent years as part of what the government says has been a successful program to quash extremist and separatist movements.