Plot: In the second episode of his series tracing the story of the most famous trade route in history, Dr Sam Willis travels west to central Asia, a part of the Silk Road often overlooked and yet the place of major innovations, big historical characters and a people - the Sogdians - whose role was pivotal to its success. In the high mountain passes of Tajikistan, Sam meets the last survivors of that race, who once traded from the Mediterranean to the China Sea