The earliest steps that led to the exchange of ideas, skills, and material goods between the cultures of the East and the West will probably never be more than a matter of surmise; but the literary and archaeological sources of information that start as a slender trickle at the beginning of the Christian era soon develop into a mighty stream and disclose a tale of human endeavour and ingenuity which few historians can fail to find fascinating and stimulating. During the last half-century or so dedicated scholars such as Pelliot have devoted their major research efforts to the meticulous consideration of the minutiae involved in the subject; and, more recently, Joseph Needham has contrived both to continue the work of such predecessors and to draw some of the major conclusions that are the fruits of basic research conducted in several disciplines. Probably the full story of these exchanges can never be told; for the evidence is sadly deficient; balanced inferences that rely on information gathered from both East and West are rarely possible; and, maddeningly enough, the political restrictions of the 20th century now prevent the application of the modern techniques of archaeology, geography, and anthropology in areas where they are most likely to be successful.