Well when I went to University in the US just a few years ago I noticed that especially Indians were much brighter than the American students. I as a Norwegian was an average student in math. Another interesting fact that you wrote was that they barely knew the language. That means that they have to work harder and be smarter to get the same scores, but they did better. I know since I studyed in the US and know how language barriers makes thing harder. Since I am from Europe it is not that big a deal, but for other people from China it must be very hard.
You dont have to speak english to solve a differential equation.
That is my general experience with Norwegians!! (Heh. I am married to one. You should see her when she balances her check book. Very traumatic...).