My friend, however, came a cropper.

After dabbling in a hallucinogenic tincture, the name and composition of which permanently escapes him, he ended up howling at monkeys in jungles and talking to tropical plants before falling off a train. He returned home with two smashed legs and one mashed mind. But although he is scarred for life mentally and physically he still, in rare moments of lucidity, speaks of the joys of his adventure and how he believes it was the making of him.

During the writing of the recently-released Magic Bus: On the Hippie Trail from Istanbul to India travel writer Rory MacLean met many people who held the "hash and hepatitis" trip to Asia from Europe to be responsible for their subsequent successes.

Like the Danish member of parliament who tells him: "The hippie trail? I wouldn't be here now if I hadn't hitched to India in 1967."

That year the Indian government estimated there were 10,000 youthful foreigners in the country. Then the Beatles came looking for the Maharishi in Rishikesh and by the end of the decade the same number, in search of enlightenment and cheap drugs, were flowing over the border from Pakistan each week having travelled the trail. It stretched along much of the old silk road from Turkey through Iran, Afghanistan, Pakistan and into India. Along its length rocked and rolled a series of weird and untrustworthy buses ferrying the long-haired, bead-laden hippies reading Carlos Castaneda and Siddhartha by Herman Hesse and listening to the music of The Grateful Dead and Crosby, Stills, Nash and Young, all the time searching for the keys to their own Utopia.

Many were inspired by the works of Jack Kerouac and Allen Ginsberg who - following in the footsteps of Byron and Shelley who had inspired the Grand Tourists to visit Rome and Greece, then the meeting point of Classical and Contemporary culture -- wanted to push back the frontiers both in the mind and on the road.

While few have returned having actually found Shangri La, many have became better people. Chris Weeks, who drove along the trail with travel company Intertrek, tells MacLean that while many westerners he encountered were there for cheap thrills, he and countless thousands were awakened to the tribulations they had been sheltered from in their cosy, suburban homes. "I saw that most people in the West have not got a clue about how the Third World lives: the deprivation, the corruption, the lack of medical care and water. Really, what life is about. Doing the trail was possibly the best thing I ever did for myself. I came home better equipped." Or there's John Butt, the Bob Dylan-loving, Muslim chaplain of Cambridge University who converted to Islam while wandering in the Punjab in 1969.

But in his journey along the route, made about three years ago, MacLean also encounters once idealistic travellers who, having originally departed embittered at the ways and means of the modern, western world, are now embittered about the commodification of travelling. Take Desmond, a once-rootless Englishman who he encounters in Nepal: "Kathmandu is now full of people reading the Lonely Planet guide to Vietnam. I mean, at their age we wanted to get into each other and society, not to live in a meltdown world. We didn't have guidebooks, we didn't even know the name of the next country. 'What's this place called? Bhutan? Where the hell is Bhutan?'" Desmond perhaps epitomises the observation from Chinese writer Lin Yutang that "a good traveller is one who does not know where he is going to and a perfect traveller does not know where he came from."

MacLean concludes that: "Rather than inspirational, the travel market is now aspirational." He writes that now we take drugs that extend mortal life rather than spiritual horizons even as we renew our annual travel insurance policy.

So the travellers have changed, but what about the countries visited?

By far the most interesting portions of the book deal with the effect these travellers had, and are still having, on the countries they venture through, often in a haze of adventure and ignorance. MacLean quotes Bruce Chatwin's observation that western travellers may have hastened Afghanistan's descent into anarchy. Chatwin's theory was that the peace-loving hippies influenced Afghans in their ready embrace of Marxism, hence paving the way for the Soviet invasion. Conversely, MacLean suggests that the casual morality of young westerners enraged traditionalists in Iran, stirring an Islamic reawakening culminating in the 1979 revolution when the Shah was deposed.

MacLean writes: "We know our lives are bound by the acts of armed men, in and out of uniform. But what of the link to the hundreds of thousands of casual young westerner travellers, initially in flares and open-toed sandals? We tread in their footsteps in swelling numbers and arrogance, turning the world into a commodity, insulting -- even enraging traditionalists, stirring in them a zealous Islamic reawakening. Is it coincidence that the Muslim countries that so many travellers breezed through -- among them Iran, Iraq, Afghanistan and Pakistan are now political minefields?"

The bikini tops, the alcohol, the drugs, the relative lack of respect for elders and, in many instances, the conspicuous consumption of the western travellers would be anathema and antagonistic to many already reeling from the insidious Disneyfication of the world and the increasing reach of the resource-grasping western corporations. MacLean suggests that the once-unlimited frontier has been reduced to a series of war zones and annexed mountain states where veteran travellers moan about the absent spirit of adventure, while many locals resent the intrusion of the dollar-wielding outsiders.

So the spirit of the 1960s has probably been lost forever: the true trailblazers are, as MacLean suggests, those who take responsibility for their actions and who appreciate their power, and who travel in a manner that benefits local communities even if caution does limit their scope for daring.

Perhaps then, amusing as it may be to the locals, there will be no more drug-addled westerners howling at monkeys and talking to plants.

David Sanderson is a correspondent for The London Times.