It's amazing. Admittedly that's not a judgement based on normal filmmaking standards, which in a sense don't apply even though this won six film festival awards... but it had me spellbound. It's so alien! If you're interested in broadening your mind with foreign movies, they don't get much more foreign than this.

It's Iranian, about Kurdish refugees in the desert. They're just wandering. They were at Halabja when Saddam Hussein used his chemical weapons there during the Iran-Iraq war. The title is a reference to the blackboards being carried by our protagonists, who are itinerant teachers, trying to scratch out a living among their dirt-poor illiterate fellow travellers. This is nearly impossible. Hardly anyone can read or write and even those who can are unlikely to admit to it, because they've been told not to trust strangers. Furthermore, almost no one they meet even wants lessons. Think about it. You're a goat herder in a wilderness. You're so poor that your currency is liable to be bread crusts and walnuts instead of money, you're shot at by soldiers on a daily basis and you're living in a landscape where almost nothing grows.

In other words, this isn't anything I'd recognise as civilisation. That's no reflection on the people themselves, who are as intelligent as any other group of human beings, but they're existing at a subsistence level in which all effort has to go on staying alive. Occasionally one of them will own something high-tech, such the child with a pair of binoculars, but otherwise it's hard to imagine life in the Middle East having been much different thousands of years ago. Well, apart from the bullets and landmines.

That's extreme. Just being with these people is an experience, but what really took me into the Twilight Zone were the teachers themselves. The first thing we see is nine or ten figures in the desert with blackboards on their backs. It's surreal. You'd think they were aliens! It's such a strange silhouette, turning them either into tortoises or big, rectangular birds. It also changes their behaviour and body language, so a teacher saying goodbye to another teacher will do so in a peculiar fashion, or alternatively a group of teachers being shot at will run away and all hide together under their blackboards. That's immediately startling, but just as freaky throughout the film is the sight of these teachers trying to teach. "Would you like to be able to read and write?" "No." "Why not?" "It's useless." They keep plugging away at their lost cause and you wonder how long it'll be before they starve to death. A few days, probably. Frankly, they'd do anything. Teaching is their trade, but they'd tap dance barefoot across hot coals if there were a handful of walnuts in it for them.

The film has two teacher-heroes, although for an embarrassingly long time I didn't realise this. I thought one teacher was dividing his efforts between two groups of people. It took something visible to happen to one of their blackboards, whereupon I suddenly had a visual clue to kick my brain into gear.

As for the acting, it's invisible. The film feels like a documentary, which is essential since its verisimilitude is what makes it compelling. Samira Makhmalbaf uses a lot of non-professional actors and achieves remarkable results with them.

It's worth saying a few words about Makhmalbaf. She's staggeringly young. She wrote and directed her first movie, The Apple, when she was eighteen, then took it to Cannes. It won a bunch of film festival awards, plus the British Film Institute's Sutherland Trophy. Only two years later, she made this. There's a reason, of course... her father, Mohsen Makhmalbaf, is a film director too. Samira left school at fifteen and started helping him make films instead. That helps explain how she managed to be capable of all this, but even so I'm still in awe at her achievements. You'd never believe that this was the work of a twenty-year-old. It feels stronger and more mature than that, combining a documentary tone with fiction to achieve an effect that you'd expect to be the highlight towards which other directors might dedicate their entire careers to attaining.

There are some remarkable scenes. There's one in which a teacher tries to read a letter to its anguished owner, despite the fact that neither of them even recognise which language it's written in. There's also a wedding, which had me in fits. Just try to imagine what marriage might mean to these people. You're not going to get close, but at least try.

The closing credits astonished me by saying that this is a Japanese co-production. Takeshi Kitano gets a credit. More precisely, Italian and Japanese companies helped to make this movie. Would I recommend it? Hell, yes, and backing me up are half a dozen film festival prizes from Cannes, Italy, Paris and the American Film Institute. It feels like a mind-blast of a documentary, but Makhmalbaf has said it's "something between reality and fiction. Smuggling, being homeless, and people's efforts to survive are all part of reality... the film, as a whole, is a metaphor." Overall, it's thought-provoking and impossible, because it's real. Often surreal, sometimes funny, usually appalling. Put it on your secret nuclear Christmas list.