I personally think it is silly to have any ethnic purity (Neo-Nazi version) I mean it is one thing to preserve the culture and teach your children of your culture, but trying to keep your "race" pure? What is pure anyway? I don't think any of us are truly "pure" in our ethnic background. I'm sure we have a couple of rogue family members marrying other "race"
The Chinese have close off to the world before and look what happen to them (so did Japan) we are an international market now. We will have to deal with other country, this mean interaction. People WILL meet other people and eventually fall in love and marry. It is going to happen. Forcing any purity is just going to cause more violence even the Mongolian doesn't believe in violence.
Which brings me to my next point. How can you not be violent? What if your sister (Mongolian) met a Chinese guy and married him? then what? with no violence, you just shut him out? he is no longer welcome in your home? that is just going to cause isolation and eventually stagnation, and then the village will die out.