Modern silk making in China

In the final episode of his series tracing the story of the most famous trade route in history, Dr Sam Willis continues his journey west in Iran. The first BBC documentary to be granted entry for nearly a decade, Sam begins in the legendary city of Persepolis - the heart of the first Persian Empire.

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, to a part of the Silk Road often overlooked and yet the place of major innovations, big historical characters and a people - the Sogdian's - whose role was pivotal to its success. He travels through Tajikistan to meet the last survivors of that race and discovers how they were built by armies of captive craftsmen for one of the greatest conquerors the world has ever seen: Timur. He then goes back to school to learn where modern mathematics and astronomy were born.

Tracing the story of the most famous trade route in history, Dr Sam Willis starts in Venice and explores how its Renaissance architecture and art has been shaped by the east and by thousands of exchanges along the Silk Road, from Venice to China's ancient capital, Xian.