Yeah, how would China Invade?
There are no feasible land routes into India.
Through Nepal - the interface between China and India
"Germany can't invade France, the Ardennes is impassable!"
"Hannibal can't invade Rome, the Alps are impassable!"
The Chinese are smart cookies, they'll figure it out.
Any army India has on paper is just that - a paper army which will collapse under a light breeze. They're a horde of barbarian tribes who all hate each other