Shot in the Utah desert, downwind of a nuclear test site, the film attained greater infamy as the production on which half the personnel succumbed to cancer allegedly linked to radiation — Wayne eventually included.

According to lore, Genghis (or, if we are to pronounce him correctly, "Chingis") was responsible for many deaths besides. "The greatest happiness is to vanquish your enemies, to chase them before you, to rob them of their wealth, to see those dear to them bathed in tears, to clasp to your bosom their wives and daughters," quoth the man himself in one of his lighter moments. Between 1206 and his death in 1227, he led his hordes on a rampage unparalleled in destruction, sweeping from the steppes to the fringes of Europe, slaughtering millions, getting thoroughly medieval.

"Genghis Khan is one of the most unpopular names in Russia," recounts the film director Sergei Bodrov. "I read only bad things about him and the Mongols in my schoolbooks: barbarians; primitive, cruel people; almost monsters." By the time Genghis's grandson had taken over the family business (Kublai Khan, he of the pleasure dome), the Poles and Hungarians, too, were but a twitch of a FuManchu moustache from obliteration. The shock waves continue. Western collywobbles over the rise of Asia seem to spring from something more deep-rooted than mere trade.

Great stuff for a film-maker, though. Next month sees the release of Bodrov's epic film Mongol, the first part of a proposed mighty trilogy. Deservedly nominated for a best foreign film Oscar, this Russian/Kazakh co-production was shot on the remote grasslands of Kazakhstan and Mongolias Inner and Outer. It's a homegrown affair, featuring panAsian leads and a legion of Central Asian extras, with the dialogue entirely in Mongolian.

Others have tackled Genghis cinematically — Omar Sharif put on the marmot fur in a 1965 swashbuckler, and there was a 1998 Chinese biopic, among several others — but Mongol aspires to be the most authentic take. "I found a great story about his childhood," Bodrov explains. "He wasn't born a monster. It's good to swim against the current." At a time when a strong man has again emerged to lead Bodrov's homeland, celebrating the life of a tyrant admired openly by Hitler might be considered questionable. "He was defamed and stereotyped in Russia and in the West," Bodrov points out. "In Central Asia, he is a hero."

When the end product is as magnificent as Mongol, it's difficult to argue. A sumptuous, cast-of-thousands extravaganza (shot on a laughably knockdown budget of less than £10m), it easily rivals The Lord of the Rings, Hero or Crouching Tiger, Hidden Dragon for sheer scale and mysticism — but all, of course, based in reality.

Unusually for a subtitled film in an obscure tongue, Mongol is being given a wide release in Europe and America, with the spectacular battle scenes— the work of its Kazakh and Kyrgyz stunt riders — played up in the trailers to woo the acne brigade. Still, it is the human story that shines through. In the film, we meet nine-year-old Temudgin (Ghengis's given name), on his way to bag a bride. After the murder of his father, Temudgin ascends from petty cattlerustler to tribal avenger (played by the cult Japanese actor Tadanobu Asano), abetted by his prone-to-kidnap wife, Borte (Mongolian first-timer Khulan Chuluun), and blood brother Jamukha (the Chinese actor Honglei Sun).

A case of revisionism? "I would certainly hope so," says John Man, the British historian whose book Genghis Khan: Life, Death and Resurrection became Bodrov's definitive reference. "It's not revisionism in that you can downplay the deaths or the drive for empire, but you can see where it comes from." The film concludes with Temudgin anointed Genghis Khan ("Supreme Conqueror"), an act he celebrates with the genocide of the rival Tangut nation — though we can forgive him that for the lack of a strong male role model.

It seems Genghis has been misunderstood all these years. The reason, Man explains, is archival: in this case, history being written by the vanquished. "And the victims have a one-sided view," he says. For the Mongols, illiterate nomads, there had been little point in getting their antics down on paper. It was only in the late 19th century that a cryptic Chinese tome, The Secret History of the Mongols, resurfaced, and as recently as the 1980s that the most complete western translation of it emerged. Comparable to the Iliad or the Norse sagas, it offers a more lyrical, romanticised portrait of Genghis than anything available previously.

Genghis may have started out as "little more than a gang leader in a turf war", as Man puts it, but within 20 years he was running a manor that took in, in today's terms, Mongolia and all of the Central Asian republics, as well as parts of Russia, Iran, Pakistan, Afghanistan, India, China and North Korea — the largest contiguous land empire ever known. "This demands some sort of explanation," Man insists. In founding the Yuan dynasty, Genghis also forged a unified China, his single greatest legacy.

Without question, Genghis's power came from his military genius — but raising a nation of mobile cavalry warriors tells only half the story. The current thinking is to construe him as a meritocratic liberator: a man who respected loyalty, displayed religious tolerance, appreciated strong women, codified laws. Given his eventual delusions of grandeur, a sort of prototype Napoleon, then? Man draws a better analogy: "It's as if Geronimo had unified the Indian tribes, taken on North America and won, then spread his empire to such an extent that Russia and Europe had somehow to come to an accommodation with him. The

surprise of seeing Geronimo in the White House would be as surprising as Genghis was to the rest of the world."

Bodrov's last film, Nomad (2005), was also set in Kazakhstan. When the director quips that he was inspired to make Mongol as a response to Sacha Baron Cohen's Borat, it is only half in jest. "I used to be a comedy writer. I like jokes. But I understand the feelings of my Kazakh friends, who took it very personally. I think the West is ignorant about the cultures of Central Asia."

On the other side of the old Iron Curtain, they were equally unenlightened. During the days of the USSR, all things Genghis were banned in the Soviet-run Central Asian republics, as they were in the satellite state of Mongolia. Which would explain why, in those self-same, newly independent nations, the cult of Genghis is flourishing. People latch onto him as a Braveheart-esque symbol of patriotism, a big fat bit of nose-thumbing towards their erstwhile ideological overlords. (Witness, too, the rehabilitation in Kazakhstan of Tamerlane, another brutal ruler now vaunted as some benevolent, folksy uncle.) Perhaps the most significant makeover in recent times has been in China, a place not known for embracing ethnic self-determination. During the cultural revolution, Genghis was driven underground. But with Inner Mongolia lying within Chinese borders, the solution to the Genghis problem has been pragmatic: Genghis is Chinese. "All part of one happy family," Man says.

At the height of Mongolian power, and in a seemingly older variant on the Mussolini/trains-on-time adage, it was said that a virgin carrying a bag of gold could walk from one end of the empire to the other unmolested. Probably, though, that says more about the Mongolian belief that "a horse is more important than a woman" (or, for that matter, precious metals). When Bodrov requested a few extras to turn up on location, a thousand appeared, all astride their beloved hoofed companions. Many more have shown their devotion, flocking to see the film as it has been screened up and down the Silk Road. "Mongol worked well in Kazakhstan, as you can guess. In Siberia, too," Bodrov enthuses. "In China, it will be released this year. In Russia, it worked much better than I expected. It stirred interest about Genghis Khan."

So what— as Monty Python might have put it — did the Mongols ever do for us, apart from bequeathing us the word mogul, corrupted from the Persian? It seems they gave us all an Olympic-sized headache, as it was Genghis who first incorporated Tibet into China. "It is ironic that China owes its geographic sense of identity to the Mongols, and that comes from what happened to a young man on a remote Mongolian hillside in the early 13th century," Man adds.

There are still some hazy bits about Genghis's CV, especially surrounding his eventual death at 65 or thereabouts. (Locating his burial site remains one of archeology's great quests.) Some say he slipped away quietly through illness, others that he met a more violent end at the hand of a new bride, who whipped out a pair of scissors on their honeymoon night and separated her husband from his wedding tackle. Until then, Genghis had been prodigious in that department. An extraordinary 2003 study revealed that 16m men in Central Asia carry his family's Y chromosome, one in 200 on our planet — a veritable father of a nation.

"It's interesting to try to bring him alive, to understand his character and fill the gaps," Bodrov says. If there has been compression of certain facts, essentially the boiling down of the convoluted tribal politics, he has still got it spot-on, Man says. "His achievement is to capture the spirit of the history." Genghis's demise remains two films away. Meanwhile, Bodrov's biggest challenge will come with the next instalment. In that, Genghis must trample the Muslim world. "I want to skip Part Two and make Part Three," the director says. "I'm writing it now. Don't worry, it will be dark."

So, is it really okay to lionise such a ruthless and bloody individual? We should not impose today's morality on the world of 800 years ago, Bodrov cautions. "For me, the most barbarian century was the most recent, the 20th. The two world wars, Nazi camps, Stalin's gulags, tanks, rockets, atomic bombs. . . how can we compare it to a man who was fighting with swords and on horses?"

Mongol: The Rise to Power of Genghis Khan opens on June 6