Columbia subject headings:
Harvard subject headings:
Asia, Central--History--Congresses.
Silk Road.
Trade routes--Asia, Central--Congresses.
Trade routes--Asia--Congresses.
Trade routes--Turkey--History--Congresses.
Princeton subject headings:
Asia, Central--Description and travel.
Asia, Central--History.
China--Description and travel.
Silk Road.
Trade routes--Asia.