The ancient Tea Horse Road was active with caravans until as recently as the 1960's. Precious little remains of the legendary trails – but a revival may be on the horizon.

Zhao Henian had done everything right. He had fed the horses first before eating his meals – this was the tradition among his particular band of travellers to show respect for the animals – avoided turning his rice pot upside down (as this was considered to be bad luck) and always faced the direction he wished to travel whenever he ate. But he was still hungry.

Somewhere along the treacherous Tea Horse Road (also known as the Southern Silk Road) between Yunnan and Lhasa, Tibet, Zhao and his men ran out of food.

The group of muleteers, known as mabang (mule caravans) in Chinese, was traveling along the ancient Tea-Horse Road, a term coined by Yunnan academics in the 1990s to describe the myriad of interconnecting caravan routes that cover vast swathes of Asia.

Trade is thought to have begun somewhere around the seventh century and peaked towards the end of the Ming dynasty in the 1600s. It was the job of Mabang to slog basket loads of tea from the mountain valleys of Yunnan and Sichuan to the "Rooftop of the World" in Tibet in exchange for horses.

Mabang generally followed two main routes: the Sichuan-Lhasa route and the Yunnan-Lhasa route. Originating in the Tang dynasty, the Sichuan route began in Ya'an and ended in Lhasa, via Luding, Kangding, Batang and Chamdo, where it linked up with the Yunnan section. From Yunnan, the route began in the Xishuanbanna - the site of tea production - to the Himalayan plateau - the site of tea consumption - via Pu'er, Dali, Lijiang and Shangri-La. Once in the Tibetan capital, the tea trade extended to Nepal, Myanmar and India, and as far as the Red Sea.

Yet the now-forgotten road was not constructed or planned, as Beijing's Great Wall was. It was carved over millennia, each footstep and hoof eroding the rock one nanometer at a time.

Today, most of the original tracks of Tea Horse Road have either fallen into disrepair or have disappeared completely - reclaimed by thick jungle and faded into obscurity by years of monsoonal storms. The trail lives on in the memories of the few surviving men and women who once navigated it. 80-year old Zhao Henian is one of those men. He remembers the scarcity of food on the trails around Lijiang, extending southwards to Dali and northwards to Khamdo and the Tibetan Plateau.

Tea porters' only food was a satchel of corn bread and an occasional treat - bean curd. Saving weight was a necessity to carry more tea and earn more money, and porters often carried loads weighing between 150 to 200 pounds; stronger men would carry more. According to Zhao, one pound of tea was worth roughly the equivalent of one pound of rice when they returned home.

"Although we always carried tea leaves and condiments, we were not allowed to enjoy them. Besides, the steep mountains and deep valleys prevented us from carrying enough food," said Zhao.

Each troop of mabang had their own way of staving off hunger - Zhao's method was to suck on pebbles. He would select small, porous stones from streams, fry them in pig's fat and sprinkle them with seasoning to create a kind of mountaineer's lollipop; a poor man's appetizer.

The Tea Horse Road navigated some of the harshest, highest and inaccessible trails in the world. It was up to the mabang to wind their way through cavernous gorges, cling to the edge of 17,000-foot passes – a fall from which would mean certain death – and ford iced-over sections of the Yangtze, Mekong and Salween Rivers. They connected paradisiacal enclaves would otherwise have gone unseen.

"We have gone through every difficulty you can imagine, but is not life an adventure?" said Zhao, who recalls porters dying after being swept away by torrential floods while passing through narrow gorges.

Exposure to extreme weather conditions wasn't the only concern for mabang. Bandits were a constant threat. Key watering holes along the route were occasionally poisoned, according to Zhao. It was the job of the leader of the group, known as the magoutou to carry a metal pot to test the water. If the surface of the pot became discolored after it was filled with water, it was deemed to have been be poisoned.

Swapping tea for horses sounds like an unfair deal by today’s standards; it wasn't in the Song Dynasty (960-1279 AD). At the time, Chinese-bred horses were smaller and inferior to those of their enemies – the Liao (Khitan) in the north and the Xi Xia (Tangut) in the West. With warring nomads threatening the borders of the empire, a sturdy Tibetan breed of horses known as the Nangchen became a lifeline supply to Chinese forces. (Though, in the end, all the tea of Sichuan and Yunnan couldn't save them from Mongol invasions.)

It wasn't until the Mongol rule of the Yuan Dynasty (1271-1368) that Yunnan was annexed by China. Before then, trade had existed between Chinese merchants and borderland barbarians. By the Ming Dynasty (1368-1644), thousands of Han-Chinese began mingling with local ethnic minorities and tea trade along the route was officially sanctioned. Offices for tea and horse trading called chamasi – which doubled up as caravanserai to offer shelter and protection for treasure-loaded caravans - began popping up in remote villages along the routes.

It was the Tibetan obsession with Yunnanese tea that was largely responsible for fuelling the trade. It was an obsession that began long before horses swapped hands in the Song dynasty and the roaring trade of the Ming dynasty. Tea had been transported to the Himalayan plateau en masse by Chinese monks in the Tang dynasty (601-917) who introduced it as a way to stay awake during long hours of meditation.

Drinking tea became a fashionable habit among religious leaders and the political elite in Tibet for its ability to break down grease from meat-heavy diets and promote healthy digestion. It wasn't long before the whole of Tibet was hooked.

"Even the pure copper bells on the necks of horses become extinct," said the old man with regret.

But what really worries him is that people do not believe in his experience anymore.

"Even my own grandchildren think my story is absurd and not trustworthy," he said.

Edited by Jake Hooson