Answer:
in the northwest
Explanation:
The northwestern part of China is one of the most inhospitable places for living in the country. It is an area dominated by desert and dry steppes, with the temperatures going in extremes, both hot and cold, and the precipitation is very low. Also, this is the part of China in which there's the least investment, but also the part of the country where the people (Uighur people mostly) are supervised, tortured, forbidden to use their culture and language. That has lead to lot of people from this region to either move into the larger cities, or move out of the country, thus making it the region with the highest decrease of population in China.
