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Iranian oilfields are, the others being in the north and centre. Together they are thought to comprise the world's third-largest reserves. Despite this Iran remains relatively poor due to mismanagement, corruption, mountainous topography that hinders transport connections and economic sanctions which have, in part, prevented certain sections of industry from modernising.

Iran holds what might be a trump card - the ability to close the Strait of Hormuz in the Gulf through which passes each day, depending on sales, about 20 per cent of the world's oil needs. At its narrowest point the Strait, which is regarded as the most strategic in the world, is only 21 miles across. The industrialised world fears the effect of Hormuz being closed possibly for months on end, with ensuing spiralling prices. This is one reason why so many countries pressure Israel not to act.

Modern-day Iran has no such imperial designs, but it does seek to expand its influence, and the obvious direction is across the flatlands to its west - the Arab world and its Shia minorities. It has made ground in Iraq since the US invasion delivered a Shia-majority government. This has alarmed Sunni-dominated Saudi Arabia and helped fuel the Middle East's version of the Cold War with the Saudi-Iranian relationship at its core. Saudi Arabia may be bigger than Iran, it may be many times richer than Iran due to its well-developed oil and gas industries, but its population is much smaller (28 million Saudis as opposed to 78 million Iranians) and militarily it is not confident about its ability to take on its Persian neighbour if this cold war ever turns hot and their forces confront each other directly. Each side has ambitions to be the dominant power in the region, and each regards itself as the champion of its respective version of Islam.

Iran is a non-Arabic, majority Farsi-speaking giant. It is bigger than France, Germany and the UK combined, but while the populations of those countries amount to 200 million people, Iran has only 78 million. With limited habitable space, most live in the mountains; the great deserts and salt plains of the interior of Iran are no place for human habitation.