Columbia subject headings:
Harvard subject headings:
China--History--Han dynasty, 202 B.C.-220 A.D.
China--History--Tang dynasty, 618-907.
Luoyang Shi (China)--Historical geography.
Silk Road--Historical geography.
Xi'an Shi (China)--Historical geography.
Princeton subject headings:
China--History--Han dynasty, 202 B.C.-220 A.D.
China--History--Tang dynasty, 618-907.
Luoyang Shi (China)--Historical geography.
Silk Road--Historical geography.
Xi'an Shi (China)--Historical geography.