When the first emperor wanted to unify the country, one of the major policies was to create one system of written signs. By force, brutal force, he eliminated all the other scripts. One script became the official script. All the others were banned. And those who used other scripts were punished severely. And then the meanings of all the characters, over the centuries, had to be kept uniform as a part of the political apparatus. So from the very beginning the written word was a powerful political tool.
