Looks like Yinchuan city and Ningxia province haven't Russian language elementary schools. So either your girls need to study Chinese at there, or move to other more open cities.

i work in Yinchuan. There are international kindergardens and my friend just worked at a school where she taught the Ontario curriculum. Her age groups were around 15 years old so maybe they start at 11. The school was number 2 school, they may have programme's available for them. But if you are going to be there a long time better to enroll them in a normal school with added help.