haha..i know you gonna said that...they were just oppotuniste and take advantage of China's weak period for these western nations...and ask yourself where are those Hun, Mongol, Kithan and much more...we all swallow them at the end one by one...if not because of Russia, there is no such nation call Mongolia nowaday.
As I said time will tell and hope that you will live long enought to witness how we will deal with our foes if not this century than will be the next one, Han dynasty toke more than hundred to defeat the Hun, several decade for Ming to defeat Yuan and for Manchu we're brother now so no need to dig how we score each other...what we have is time, the cycle of power will alway return back to Chinese hand.