Personally, I think the Chinese Federation didn't grow to be that big through direct conquest like Britannia did. That's because nobody cared to revolt against the eunuchs before R2. Ergo, I'm guessing that India was annexed to China some time before season one in exchange for something else (think: benevolent assimilation). So the Chinese Federation (note use of the term "federation", denoting some sort of cooperative entity).

Just placing my two cents on the line here.