Do you think I'm retarded? Obviously I mean nations other than Pakistan and India. But they both have nuclear weapons aimed at each other, which is exactly why they haven't already fought it out over Kashmir.
Kashmir is extremely mountainous which would make troop movements into the middle east basically impossible. Even the US and Canada had trouble with the mountainous terrain in Afghanistan; we have lots and lots of planes, they don't, and Kashmir is even worse. In addition to that, Pakistan and India both have ridiculously large populations (and nuclear weapons). China would not invade through Kashmir.
If China were to enter the Middle East without first invading Mongolia or Russia, they'd have to slowly (and I mean SLOWLY) move troops into Pakistan down their magnificent two-lane highway. The thing is, though: China and Pakistan are allies. Pakistan is a Muslim country, so pissing them off probably isn't going to help their bottlenecked invasion of the Middle East. Not to mention the fact that India has a total population of 1.1 billion (China has 1.3 billion) which would make ground warfare between the two countries just so very fun.
History shows that I'm not the first person to recognize the logistical problem of troop movements through the Himalayas. The People's Army stopped at the Tibetan Plateau. The Great Wall of China stops at the Gobi Desert. They'd be looking at sending their 3 million soldiers on a 2400 km trip across the worst terrain on the entire planet - impassable mountains, glaciers, deserts - and I'm pretty sure they don't have enough planes for that.
It's way more likely that China would forego the land invasion and just break out some nukes. But that's not very likely either, because a MAD situation is still a very strong reality. In fact, MAD is the very reason an invasion of any nuclear-armed country basically isn't going to happen, because the very second the situation becomes unwinnable that country will hit the big red button. WW3 isn't coming any time soon.