Columbia subject headings:
Harvard subject headings:
China, Northwest--History.
Gansu Sheng (China)--History.
Ningxia Huizu Zizhiqu (China)--History.
Qinghai Sheng (China)--History.
Princeton subject headings:
China, Northwest--History.
Gansu Sheng (China)--History.
Ningxia Huizu Zizhiqu (China)--History.
Qinghai Sheng (China)--History.