Read up on communism. They hate any forum where people can get together and discuss things outside the narrow parameters of their thought system.

They don't want foreigners influencing the people. They have qq which has more members than facebook, but the government can control that. They don't want unrest.

Some of the information from outside of the world is forbidden in China. They arent allowed to discuss / know what's going on. Especially news related to political issues are filitered. However, China is much better than North Korea, at least they can communicate freely among themselves.

The CIA tracks everything that goes on regarding users on Facebook. http://www.youtube.com/watch?v=ShQPF-KywXs&feature=related I would rather have it blocked than be monitored constantly.

The root cause of the ban stems from a central theme that China' s government does not want their people to retrieve more informations from outside and they think banning these speech and connections can make their regime more secure. They make a plausible excuse for the ban that the first priority for the government is to make all people not starved.