The connection between the ideas in these sentences is one of contrast.
Explanation:
The idea expressed in the first sentence is connected to the idea in the second sentence by "however". "However" expresses contrast. Its purpose is to introduce an idea that goes against or contradicts another idea expressed earlier. In this case, the first idea is that Gutenberg invented the printing press. The second idea contradicts it by stating that there were earlier versions of the press in China, before Gutenberg. That is why "however" is used.
