And they weren't all Europeans. Americans and Canadians crossed the Atlantic to take part, Australians and New Zealanders had a strong backpacking tradition and found the route convenient. Westerners of all nationalities were represented.
They had many reasons for going: some sought spiritual enlightenment, some were escaping from a rigid conventional lifestyle, some saw opportunities for profit, and some just wanted to see the world. They all had a sense of adventure, but not all of them could be described as hippies - many were simply keen to explore the overland route to the east, first blazed by Marco Polo.
But from the late 1960s onwards the largest contingent, united by a common interest, were the young people with long hair who gave the hippie trail its name - and what defined the hippie trail was that it led to the major hashish-producing centres of the world.
Afghanistan, Chitral, Kashmir, Nepal - familiar names to the pot-smokers of the sixties and seventies, most of whom knew very little else about the countries where their herb of choice was cultivated. But for the next ten years or so they set off in their thousands to look for it.
Overland bus companies sprang up to cater for them, advertising cheap tickets in the "underground press". They shared the road with a motley procession of private cars, vans, minibuses, even motorbikes. Many vehicles never made it all the way, and many more never made it back. It was, after all, a journey of over 6,000 miles in each direction, and it took in high mountain passes, scorching deserts, and some very rough roads.
Popular legend tells of the Magic Bus that left from Amsterdam - except that it never did. The company was merely a booking agency and didn't actually own any buses. Passengers were found places aboard the scores of independent coaches that plied the route. Other companies such as Budget Bus did actually run their own small fleet of vehicles.
Public transport was another option. Although the railway in those days ended in eastern Turkey, from Istanbul onwards there were cheap local buses, and western drivers also picked up passengers from the city's famous Pudding Shop, where rides in independent vehicles could often be arranged. Access to cheap rail travel resumed in Pakistan and India.
People also hitch-hiked, particularly on the way home, though this was usually only possible in Europe, and the cost of public transport was extremely low in Asia. Westerners who could drive were sometimes paid to take vehicles from Germany to Lebanon or Iran, another way of affording the trip.
The Hippie Trail Route
The route of the hippie trail essentially started at Istanbul, the point at which all roads from Europe converged. From here the direct route led straight across Turkey, though some headed south for Lebanon, for centuries the main hashish producer of the Middle East.
From Turkey the route continued across Iran, then a secular country run by the Shah, and on to Afghanistan, the first major destination of the hippie trail, a land where foreigners were made very welcome and where a large proportion of the population used hashish themselves.
After Afghanistan the trail offered many diversions. On entering Pakistan some would head north towards Chitral, but the majority crossed the country and entered India, where a trip up to Kashmir was an immediate option for enthusiastic potheads. Northern India also offered Manali, another popular destination for hippies and another centre of marijuana cultivation.
In winter months most hippies would head south for the beaches of Goa, where hashish was always freely available (though it was not actually produced there). But in the summer the hippie trail ended in the mountains of Nepal, where until 1973 there were many hashish shops operating legally, and where there was no real difficulty obtaining the world's finest charas afterwards.
Visas, where required, could be obtained easily at the borders or towns en route. British passport holders did not require a visa to stay in India long-term.
Always A Freak - Never A Hippie
Those who went on the hippie trail often referred to it as "going to India", a shorthand way of describing the trip. They did not call themselves "hippies" anyway, preferring the term "freaks", and in Kathmandu everyone knew where "Freak Street" was (though the official name was Jochen Tole).
While other travellers - those who were not "freaks" - quite reasonably refer to the route as "the overland", there really was a distinct hippie trail. In every major stop along the way there were hotels, restaurants and cafes that catered almost exclusively to the pot-smoking westerners, who networked with each other as they wandered east and west - there were no Lonely Planet guides in those days, and (of course) there was no internet.
This influx of long-haired western youth must have been a curiosity to the locals, who were largely unaccustomed to tourists of any sort back then. But they were generally hospitable, and many found welcome ways to derive extra income. Their experience was caricatured in the 1971 Bollywood movie Hare Rama Hare Krishna, which featured a scene involving chillum-smoking hippies, accompanied by the enormously popular Asha Bosle song Dum Maro Dum.
The hippies tended to spend more time interacting with the local population than traditional sightseeing tourists - they had no interest in luxury accommodation, even if they could afford it (which few could), and some would "go native" after a fashion, particularly in India. Of course, they were still tourists really, albeit of a different sort, and hedonism was the primary aim.
There were casualties, undoubtedly. Staying healthy could be difficult, particularly in Afghanistan, and even hippies can suffer from culture shock. Some would get severely ill, or run out of money, and have to be flown home. Others would wind up in jail, not a pleasant experience anywhere and particularly tough in a third world country.
Most survived, however, and lived to tell the tale on their return, often inspiring others to follow in their footsteps. And a few stayed on, found ways to support themselves, and still live in India.
The End of The Road
The classic hippie trail came to an end in 1979, when Islamic revolution in Iran and the Russian invasion of Afghanistan closed the overland route to western travellers. Lebanon had already lapsed into civil war, Chitral and Kashmir became less inviting due to tensions in the area, and even Nepal eventually lost its peace and tranquility.
Air travel had by now become affordable and Goa became the main centre of the hippie scene, based around the village of Anjuna, where hippies had been renting houses for many years before any hotels were built to accommodate the massive influx of tourists in the 1980s.
Those who flew to Goa in later years to partake of the hippie lifestyle doubtless enjoyed themselves, and the more adventurous will have travelled around India and learned from the experience. But the overland hippie trail, which lasted little more than ten years, was gone forever.