Silver plate showing Sasanian King Shapur II, who ruled Iran, Iraq and Afghanistan. Neil MacGregor, Director of the British Museum, looks at power and faith in 4th Century Iran. He describes how an apparently secular image of King Shapur II hunting deer reveals the beliefs of the day, when the king was seen as the agent of god and the upholder of the state religion - Zoroastrianism. He explores why the belief system of such a powerful dynasty failed to become a dominant world religion. (Duration: 15 mins)