Namma

could be displayed before the gods. The tip of the shogshung glinted in the sunlight and nothing but their rhythmic chanting and the wind could be heard. It was the calm before the storm.

Suddenly, the crowd erupted into a riot of whooping and shrieking. Gunshots split the air and a blizzard of white snow clouded the blue sky as they tossed thousands of wind horses into the valley in fistfuls. They called the mountain's name, 'Amnye Kula! Amnye Kula!' over and over, and shouted their own messages to the gods, personal appeals for protection from the mountain spirits against their enemies. Gondo cried, 'Har jalo! Har jalo! Har jalo! May the spirit win!' as he cast his own paper to the wind. The chief, Tsenach, bellowed his own guttural eulogy, an enormous silver hoop swinging from his ear. Above the cacophony the deep resonance of the conch boomed out, as a monk blew into the shell and brass bells tinkled. They heaped the offerings of tsampa, rice, cloth, butter and milk that they had brought on to a huge bonfire beneath the shogshung and erected the new ndashung, stringing the prayer flags from spear to spear along the ridge and ropes tufted with merdach, spun sheep's wool, and kacher, long sheep's hair. Each man circumambulated the ridge three times on his horse and the ritual was complete. The ground was littered with thousands of wind horses and still they spiralled densely in the smoke from the fire. It was like a war.

As I watched, I could imagine it happening hundreds of years ago. The timelessness of the scene was disturbed only by a T-shirt or the flash of sunglasses here and there. Apart from the lull of the monks' earlier intervention it had been so wild, as if the men were fearlessly exposing their souls to the mountain. I had never seen such an uninhibited display of worship and was astonished to have witnessed such primitive, raw energy in the men that now sat passively around me, sipping tea.

And, of course, it had been their practice for hundreds of years – thousands, some locals said. For the Amdo nomads still embrace many of the original shamanistic and Bon disciplines of Tibet, despite their acceptance of Buddhism. In fact, Tibet was one of the last Asian countries to turn to Buddhism and the distinctive characteristics of the Tibetan variety developed in response to the strength of shamanic influence. Tsedup's father explained that their gods are divided into the protectors of nature and the protectors of religion. What I had just witnessed was a ceremony to propitiate the gods of nature.

Because of the hostility of their natural environment, it has always been the nomads' religious preoccupation to tame the land. They place great importance on optimising good luck and minimising bad luck by propitiating the gods that determine their fate. I knew that, in shamanic terms, there are three realms of existence: the sky, the earth and the subterranean. The gods live in the sky, serpent spirits live in the earth and humans live on the earth in between. The elemental nature of each domain is also important: the sky representing space, air and fire; the subterranean realm, earth and water, and all the elements being present in the middle realm.

The most powerful sky gods are those who live on the mountain peaks. These warrior-like gods, called nyen, are violent, territorial lords, who require propitiation with complex ritual and offering such as I had just witnessed. Amnye Kula takes the form of a man carrying a spear and riding a white horse, but others take different forms: for example, the mountain god, Archa, close to Tsedup's brother Gondo's tribe, takes the form of a snake.

The most sacred mountain for all the people of Amdo is Amnye Machen. It is considered the Mount Kailash, Kang Rimpoche, of eastern Tibet and its range rises out of the Amdo plains for 125 miles on an east-west axis. Amnye Machen, the mountain god, is lord above all lords of the earth of Amdo. His name means. 'Ancestor of the Amdo People', and he is the greatest and wildest of the mountain gods. But as well as these masculine, warrior gods, there are also female sky goddesses, dakinis or khandromas, who have an elementally malign nature and are said to eat man's flesh and afflict him in his sexual relationships.

The demi-gods of the subterranean realm are serpent spirits, both male and female, called lu and luma, the spirits of earth and water. In contrast to the mountain gods, who rule with patriarchal authority, the serpent spirits have a sensitive, female nature. They live in the earth, in the rocks, in the lakes and streams. They are black, white or red guardians of ecological balance, preventing human interference with the earth. Precious stones belong to them, and the power of a coral or turquoise stone, so important to the nomads in their traditional dress, is deemed auspicious or inauspicious, depending on its guardian serpent spirit's satisfaction with how it was mined and how it has been looked after. According to shamanistic belief, the mining of gold or iron is offensive to the serpent spirits, like stealing from them. Even digging a hole in the ground could risk offending them, and Tsedup told me once that his mother would not leave one tent peg in the ground when they moved to new pasture, for fear of wounding the earth. With all this in mind, it was hard to imagine a more devastating proposition than that which was presented to them when the Chinese began gold-mining recently on a holy mountain in Machu.

The middle domain is inhabited by minor gods, more intimately related to humans and their daily domestic life than the mountain gods and the serpent spirits. They have specific functions and include home gods, who provide protection for the family, a god of horses and of cattle. All of these gods need to be appeased to ensure the success and well-being of a nomad family and its herds in this hostile environment. The rituals are said once to have included animal sacrifice or marcho, blood offering, but when the influence of Buddhism prohibited this, ritual fire-offering or garchot, non-blood offering, became the favoured method of propitiation.

The shamans also believed in 'pegging' the earth. This ritual, which was adopted by Buddhist yogis, was employed to control the earth and render it submissive. The ndashung that marked the tops of holy mountains were to bind the earth and spirit powers, taming them through penetration. The mountains themselves are said to peg the earth like nails or phurbas, ritual daggers, piercing and securing it. On a human level, the chortens, stone monuments, I had seen upon entering Amdo were like symbolic mountains suppressing the demonic forces beneath them.

The other major pre-Buddhist religious influence on the Amdo nomads was the Bon religion. Even after Buddhism had replaced it, it still maintained a hold on people in areas as far away as Amdo, which had always enjoyed strong separatist tendencies, especially among the nomads.

The Bonpos also believed in taming and placating the spiritual powers of the environment, gods, demons and spirits. They were devout ritualists who, like the shamanists, sought to keep the old Tibetan gods favourably inclined to human activity. Before the Buddhists transformed the gods into part of the Buddha- dharma, the Bonpos were propitiating them and using their power to maximise human luck. As with the shamans, they focused on the earth-lords and serpent spirits, who controlled the fertility of the land, animals and their own human power, which is why it was so important to placate them.

Another Bon ritual still practised by the nomads included divination, which took many forms. Tsedup had told me that his father would sometimes burn a sockwa, the shoulder blade of a sheep, and foretell future events in the cracks left on its scorched surface.

I had learnt all of these things from Tsedup. I remember him telling me that he had never understood the need for western mountaineers to 'conquer' mountains. For him it was tantamount to hubris. He once saw a documentary about Hillary and Tenzing's ascent of Cho Mo Langma or Mount Everest, as it is called in the West. As they reached the peak, Hillary laid claim to his defeated giant with the arrogance of a big-game hunter, while Tenzing humbly gave thanks to the mountain spirit. A mountain may be tamed and worshipped, but never conquered. Even then, Tsedup's reaction to that TV documentary had seemed to me like a lesson in ecology.

Now, it was fascinating to be witnessing the propagation of these ancient rites. But as I pondered what I had seen, it struck me that I had had no relationship with the land. I'm sure that if I had grown up in the Scottish Highlands or on a ranch in Wyoming I would at least have felt a oneness with the environment, but perhaps, even then, not in the same way. I was a suburban girl. The land, the subtle transition of the seasons, the smell of the earth and real dirt right down in the skin were strange to me. Apart from the joy of a country walk, I had had no previous experience of belonging to nature. These people belonged to the land and respected it with astounding, to me, reverence. Their understanding of the transient nature of life was intrinsic, acknowledged, respected, digested. It was at the heart of nomadic life, along with the acceptance of the swift and unpredictable passage of life and death.