Why are there so many black blind people in Northeast China?

Because the climate is suitable for the survival of black blind people. In the northeast, there is a famous forest area, Daxing 'anling, which belongs to coniferous forest. The climate belongs to temperate monsoon climate, and the temperature is low most of the time. There are many species in the forest, which provide enough food for the blind. As the top of the food chain, there are fewer natural enemies, so there are many.