Well, not literally. If they did all of China, I'm sure it would take them quite a long time, considering the population. And then they'd have to stop touring and recording to make time, and they'd stop making money. It just wouldn't be worth their while, even though there are quite a lot of attractive Chinese people.
So instead they're just going to China. They'll make a documentary, do some concerts... so on.
And here's the promo for the trip:
Enjoy. It's chock full of slashy goodness.