China & Nepal

Hi! All
First of all I apologize if my ignorance offends someone concerning political affairs. It seems so complicated, so bizarre I simply do not pay attention to it. Nothing is black or white; there are 256 gray shades, and 256 more depending of the glasses you are wearing, so on and so forth, ... :-)
May be some reading this post will be kind enough to redirect me to some ... let's say ... site, where I can read a real (ops!) explanation about the following:
I never understood China's purpose when the took Nepal. Under my point of view thre's absolutely nothing there. As far as I can see (ok! I realize may be I can't see beyond my nose) does not gather any feature for such a big and powerful country to invade it. Unless China was interested in moss and lichen harvests for their Agriculture Dept. :-)))
Thx in advance