I hadn't encountered this until very recently but apparently it's quite well known. Personally I think it's a really interesting problem so I hope you like.

We assume that consciousness arises due to the firing of our neurons; neurons receiving electrical impulses, processing the information, and sending out impulses of its own. The neurons themselves are physical systems with inputs and outputs determined by their inner workings.

The concept of the Chinese brain is really easy to understand. Basically, we replace every neuron in a brain with a Chinese person. We give the Chinese people phones so that they can receive information (the analogy's version of a neuron's nerve impulses) from and send information to other people, and a list of rules which tells them exactly who they should send signals to depending on when they receive signals from, and who from.

Essentially we have replaced a brain with the population of China. The question is this: would there therefore be a 'giant blob' of consciousness floating over China; would the situation cause consciousness?