Strange stillness ... part of the staircase of the Palace of Darius in Persepolis. Photograph: Martin Godwin
The title of this exhibition is a bit misleading. Forgotten Empire, the British Museum calls its spectacular resurrection of ancient Persia. Yet the Persians are as notorious in their way as Darth Vader, the Sheriff of Nottingham, General Custer, or any other embodiment of evil empire you care to mention. They are history's original villains.
The title of this exhibition is a bit misleading. Forgotten Empire, the British Museum calls its spectacular resurrection of ancient Persia. Yet the Persians are as notorious in their way as Darth Vader, the Sheriff of Nottingham, General Custer, or any other embodiment of evil empire you care to mention. They are history's original villains.
In its day, which lasted from the middle of the 500s BC until the defeat of Darius III by Alexander the Great in 331 BC, the Persian empire ruled a vast portion of the then-known world from the Nile to the Indus. It connected the Mediterranean with modern Afghanistan. Rich beyond dreams, powerful beyond dispute, the great kings ruled from their mighty palaces at Susa and Persepolis, tolerating the religions and cultures of subject peoples and harvesting the creativity of near eastern civilisation that had already, before they came along, invented writing and urban life. It should have been enough to earn them historical immortality.
Yet, of course, the leader whose name resonates down the ages is Alexander the Great. The Persian kings, from their lofty thrones, perceived the turbulent islands on the western fringe of the empire as a marginal irritant, and yet the Greeks were their nemesis. For the Persians had the misfortune to be the others, the enemies - in short, the Orientals - against whom the first European civilisation defined itself.
The Middle East invented writing, but ancient Greece invented history. Herodotus, "the father of history", takes as his epic theme the struggle of the Greek city states against the vast Persian empire - and sees it as a war of liberation. The idea of democracy was born in the fight against Persian despotism: that is how Herodotus tells it. The Persian king Xerxes is the supreme overlord of all baddies, turning his eye on the plucky little Greek cities who, unexpectedly, fight back. Now you remember the Persians: the guys with the strange beards whom the Athenians beat at Marathon. Until Marathon, says Herodotus, "no Greek could even hear the word Persian without terror". In finding the courage to fight Persia, the Greeks discovered their own identity as citizens.
All western political theory is implicitly defined against the ghost of Persia - from condemnations of "tyrants" in the Atlantic republican tradition to Marx's caricature of "oriental despotism". In winning their nationhood, the Greeks consigned the Persians to a miserable place in the world's memory.
The most vivid portrait of a Persian ruler isn't even in this exhibition. It appears in a mosaic found in Pompeii, now in the Naples Archaeological Museum, based on a lost painting of Alexander the Great in battle. Through a tangle of horses, men and spears, Alexander charges. Darius stands helpless in his chariot, his face startled and appalled, like a frightened rabbit. So much for Persia!
This is how history is made - by writers and artists recycling stories and images down the centuries. This mosaic decorated the House of the Faun in Pompeii centuries after the fall of Darius; millennia after that, the victories of Alexander are still box office.
It takes Neil MacGregor's idealistic British Museum to put the Persian point of view. Everything about Forgotten Empire is calculated to turn history on its head. This is archaeology meeting world politics. The very existence of the exhibition is a diplomatic coup: in case you hadn't noticed, Persia is now Iran. The loans from Tehran that have made Forgotten Empire possible were negotiated before the recent change of government and had to be renegotiated at the last minute.
This is the kind of exhibition I expect of the British Museum. Here at last is the enlightening encounter with another culture that, in the Bloomsbury museum's years of decline, was replaced by crap like an Agatha Christie show. At the same time, it's laudably different from a Royal Academy blockbuster: less swank, more thought. I can promise you will not only be delighted by gold daggers and chariots but leave with a sense of Persian history. It's first rate.
So why was I disappointed? I was left flat - not by the superb show but by the Persian empire itself. The British Museum wants us to believe Persia was traduced by the Greeks. It wants to show us an alternative Persia from the evil empire vilified by Hellenic historians. Yet everything confirms this Greek "myth" of a supremely rich, powerful, bureaucratically faceless empire. The real difference between the Greek version and the version we get here is that the Greeks made the Persians glamorous in their villainy.
The Persian kings, their wives, ministers, soldiers and myriad subjects are a void at the heart of this exhibition. They don't emerge, in their own art, as individuals, only as warriors in profile, with the same neat beards. In Herodotus, the Persian ruler Darius, when he was told of Athenian support for rebels in Asia Minor, called for his bow, took an arrow, shot it into the air and cried: "Grant, O God, that I might punish the Athenians!" Compare that with the real voice of a Persian king, on a clay tablet telling of the construction of the palace at Susa: "Saith Darius the King: Ahuramazda, the greatest of the gods - he created me; he made me king; he bestowed upon me this kingdom, great, possessed of good horses, possessed of good men ..." The Greek fantasy of a monarch convulsed with anger, demanding his bow, is so much more dramatic, more human.
The same contrast between Greeks and Persians is unavoidable when you contemplate the most imposing monuments here. Unfortunately, they appear in a 19th-century collection of plastercasts; the reliefs that survive on the ruins of the palace at Persepolis are inaccessible, unless you fancy a trip to Iran. I find it hard to enjoy reproductions. Nevertheless, some judgments are possible. The celebrated frieze of various peoples paying tribute is imposing. But the figures have a static quality. No one runs, nothing overlaps. Even the wonderful carving of two immense lions, or the black stone mastiff from Tehran - an original - succeed through mass rather than movement.
If you wanted to claim, as a newspaper did this week, that Persia was "the greatest of all ancient civilisations" you'd be better off picking a venue other than the British Museum. Just a walk from the show are the Elgin Marbles - the frieze of the Parthenon created after the Athenian acropolis was razed by the Persians. The Greek masterpiece is full of motion and emotion, from horses barely reined in, to a heifer being led to sacrifice.
Where's the passion in Persian art? Its very beauty - and it is beautiful - lies in its strange stillness; you see this most in the painted brick profiles of palace guards. Yet this praise has to be qualified. This kind of glazed brick decoration isn't original to the Persian empire; they got it from Babylon - to be precise, from the neo-Babylonian kingdom that they subdued. This isn't about east versus west. With our idiocy being what it is, the British Museum runs a risk of confusing us into equating Persia with the near-eastern origins of civilisation. The Persian empire followed, and conquered, the Assyrians and neo-Babylonians - and was about two millennia after Ur. All these cultures were greater than Persia's, as a quick tour of the British Museum will indicate.
The Persian empire was admirably curious about the cultures it absorbed: in Egypt the Persian kings paid homage to Egyptian gods. It assimilated the cultural heritage of the entire eastern Mediterranean world, including that of Greece; a wonderful silver and bronze amphora handle in the shape of an ibex rests on a mask of a Greek satyr. But all this openness has an emptiness at its heart. No one is even quite sure what the Persians believed - how strange, in an ancient world so full of gods, from Osiris to Zeus to Jehovah, that only a single case is filled with religious offerings. Were they just boring bureaucrats?
Yet we do get a glimpse of what they loved. They liked to live it up. The most startling things here are gold and silver drinking vessels in the shape of horns - just a taste of the opulent lifestyle of the Persian court. That, too, becomes a little offputting as you admire one gold bracelet too many.
It sounds as if I'm kicking against this exhibition. I suppose I am, yet it is archaeology at its most impressive. You might even say it is archaeology versus history. The Greeks wrote history. The Persians are recovered here through archaeology - the study of objects retrieved from the sand. Yet history wins. The Persian empire visible in its surviving artefacts turns out to be as grandiose, luxurious and remotely despotic as Herodotus said it was.
· Forgotten Empire: The World of Ancient Persia is at the British Museum, London WC1, from tomorrow. Details: 020-7323 8583