It didn't really. News did of coarse spread, perhaps through explorers or other such. We were, however, much less unified than we are now. Exactly how far back are we talking? Also, when nation would go to war, and one would win and take over the other, they had to adapt. That culture stayed with the nation maybe weather they broke free, or whatever. For example, when Ireland was overthrown by England, they had to learn to speak English. While Ireland is no longer ruled by England, they still speak English, in most areas that is.