Censorship and killing people who were too "out of line" were staples of human civilization ever since we started figuring out governance. What's unique about China is that it was a pioneer in capturing this new technology and using it to their state's advantage. Never before in human history could you monitor all the things people said to one another, all the money that got exchanged, all data that's uploaded and downloaded, and have automation that ensures that everyone's information is looked at. The internet had become a tool of centralized control, China just was successful at realizing it first.