(The following draws extensively from an online text titled "The Record of X on the Rise of the Chinese Hacker", supplemented from other sources.)
China's earliest online community arose in the mid-1990s, with a small number of people using PCs and dial-ups to interact with each other on bulletin-board systems. Between 1994 and 1996, BBS servers proliferated in major Chinese cities, and interest in copying software and breaking license controls on software also grew, creating the first generation of Chinese hackers.
Internet access came to China in 1996, and the BBS culture moved from dial-ups and isolated servers to the internet. It is interesting to me that the BBS format is incredibly prevalent on Chinese websites today, while they have been basically replaced by social networks in America. It was during this period that a man named Gao Chunhui created the first personal website in China, and it is said that his personal site at that time was dedicated to the topic of breaking software registration controls.
This era also saw a brief period of phreaking (电话飞客), but advances in telecom technology rapidly put an end to that.
In 1998, a Taiwanese student named Chen Ing-Hau released the Chernobyl virus, which caused billions in economic damage in mainland China. Because the author was a Taiwanese student, some Chinese users perceived the damage done by the Chernobyl virus as a politically motivated attack.
Also in 1998, amid the deepening Asian Financial Crisis, there was widespread violence against ethnic Chinese in Indonesia. Chinese internet users formed teams that flooded Indonesian government email accounts, and they tried to bring down Indonesian websites with ping-based DOS attacks. In order to coordinate these attacks, a group was formed called the Chinese Hacker Emergency Meeting Center (中国黑客紧急会议中心). This might be considered the first Chinese hacktivist alliance.
So, from the very beginning, Chinese hacking has been closely tied to nationalist sentiments.