After 1127 it fell into the hands of the , and after 1235 it came into the possession of the.
The site has considerable historical significance as the first mosque was built here in the reign of the Ming Emperor, Yongle reigned 1402-1424.
Since then, authorities have taken measures to improve air quality, which have largely been successful.
Ground objects are clearly distinguished and the horizon line is visible.
The guidelines for prevention and control of overweight and obesity in Chinese adults.
Retrieved July 5, 2018.
Sci Total Environ 650:1665—1670.
In 2011, using Chinese statistics, the reported that Lanzhou had the worst air quality among eleven western Chinese cities.