Yazd is said to be the ‘oldest living city on Earth’. This might be a difficult claim to verify, but it is widely believed the site has been continually inhabited for about 7000 years. Its position on important trading routes and a tendency towards diplomacy go some way to explaining Yazd’s longevity. The fact that commercial prosperity never really translated into real political power is probably another reason. When Marco Polo passed this way in the 13th century, he described Yazd as ‘a very fine and splendid city and a centre of commerce’. It was spared destruction by Genghis Khan and Tamerlane, and flourished in the 14th and 15th centuries, with silk, textile and carpet production the main home-grown industry. Like most of Iran, Yazd fell into decline when the Safavids were defeated and remained little more than a provincial outpost until the last shah extended the railway line to Yazd.