They erected the white tent and we continued up to the craggy heights of the mountain top, abandoning the horses when the route became inaccessible for them. The rest of the way we managed on foot, scrambling among the shale and rocks, pausing to gasp for oxygen, which was sparse at this altitude. The view from the summit took our breath away. Below us was the great grassy desert of our home. Beyond, the Machu river snaked between the flatland and the undulating mountains, which receded into an azure horizon. The tribe's tents formed a circle in the middle of the scene, smoke drifting from each tiny roof and the black and white dots of yaks and sheep formed pointillist brush marks on the canvas.

We were making history. No woman had ever before set foot on Amnye Kula. We sat in silence on a rock beneath the men, and as I watched the rain-stained prayer flags fluttering in the wind, I felt a deep sense of humility. Rhanjer and our neighbour, Namjher, had arrived on horseback at the summit, from the east. We sat and watched as the men heaped their offerings of tsampa and butter on to the platform of rocks and soil and lit a fire underneath using sheepskin bellows. Each one began to mutter rhythmically, calling on the mountain spirit to protect them. Some were more vocal than others, crying out then resuming a hypnotic chant, delivering their own personal messages to the mountain. All the while they tossed into the sky fistfuls of wind horses, which caught the breeze and danced down into the dark valley behind Kula. Namjher fired off a round from his pistol and they all fell silent as we sat among the paper snow, watching the black stormclouds roll in from the northern mountain range.

We returned to our camp and lit a fire, which proved difficult as it had begun to hail gently. We girls bundled up in blankets inside the tent, while the boys braved it, squatting in their tsarers around a bubbling cauldron of tea. Then the sky sealed over in a thick, grey shroud and the wind quenched the thin flame. Most of the men set off for home on horseback, leaving seven of us to brave the night. Tsedo sat for the remainder of the afternoon feeding the fire with the bellows, hunched in the snow in his tsarer and Stetson. He didn't seem ruffled, just puffed at his cigarette for hours, and I realised that this was no big deal for him. A bit of light snow and a sharp wind were nothing compared to a harsh Tibetan winter in the mountains with his flock, where temperatures can reach below zero.

That night was a veritable tuckpa of arms, legs and feet. The tent, which had been made to sleep two comfortably, now seemed inadequate. The competition for space under Ells's British army-issue survival blanket, which resembled a sheet of tinfoil, was tremendous. We had consumed the botde of Veuve Clicquot that they had brought and were comfortable for about an hour, until its effects had worn off. I lay contorted in the dark, remembering the last time I had drunk champagne. It was at a celebrity-packed party for the magazine at the Mirabelle. I had worn my wedding chuba and the massive coral ring Annay had sent me. Lying on top of the holy mountain, I felt divorced from that previous world. I came round to the poke of a toe in my bottom. Reality was a cauldron of tea, more bread and a wet tent full of nomad cowboys.

Midway through our pretence at slumber, Chloё and I needed to relieve ourselves. We slunk out of the tent into a pea-souper of a fog and, as we squatted in the blackness, were alarmed to hear horses and men's voices. Then a gunshot. We tugged at our jeans as torchlight pierced the mist and swung in our direction. Petrified, we split for the tent only to meet Tsedo, rifle in hand, reassuring us that it was only some wandering nomads who had stolen some yaks and were transporting them undercover of night. A restful night's sleep was thus assured.

We woke again at daybreak, disentangled and washed in the mountain stream. After more tea we took down the tent and saddled up. The men led us down the sheer mountainside by the reins, as we lay horizontal in the saddle for balance. Back on flat valley ground, Tsedo shot a prairie dog for no particular reason. It seemed that despite his compassion for the sheep he killed, he also enjoyed the odd hunt. This was a man's world, and although we girls were appalled by his savagery, there was something about the masculinity of it that appealed.

A few days later we made a pilgrimage to a religious festival. But it was not an average pilgrimage, as we soon found out. The town of Tugsung Lhamo was two hours away by road, and on that chilly morning, about twenty bikers converged on the crossroads in the middle of Machu, revving their engines. Everyone was dressed in their tsokwas with their heads wrapped in balaclavas and scarves. Tsedo and Gondo took Chloё and Ells on the back of their bikes and I hopped on behind our friend Wharden. We sped out of town in a convoy, straight through a swollen river, lifting our feet in the air to keep from getting soaked. Gondo, feeling particularly chivalrous, commandeered a passing horse from a nomad and ferried Chloё across. All the way, the boys overtook each other, speeding forward then dropping back. I passed Ells who grinned excitedly, cheeks flushed, clinging on for dear life. She had developed a Tom Cruise fixation and was singing the theme tune to Top Gun right into Tsedo's ear. 'Take my breath away,' she wailed, before the wind choked her.

Tugsung Lhamo was an old town that nestled in the crook of a green valley, and spread on up a hill to where its monastery stood. When we arrived it was packed with pilgrims. They had come from far and wide for the annual event, Rughda, and were all dressed in their finest costumes and jewellery. We followed the train of chattering people up through the town, over the bridge of a stream and past white chortens until, breathless, we reached the top. The monastery and its surrounding buildings resembled those I had seen in Labrang. Their white walls sat close together in a jumble of dwellings. Opposite the main monastery building was a steep slope where everyone had congregated under the tall pine trees. Men, women and childrenjostled for a patch of ground so that they could see the performance. In the courtyard of the monastery in front of us, rows of magenta-clad monks were sitting on the steps under the huge black banners of the overhead balconies.

In the cobbled square two monks, dressed in yellow, were dancing. As they spun round, their skirts spread like twirling umbrellas and they stared out at the crowd through the white-painted eyeballs on their brown masks. They were enacting the story of Milarepa and a monk bellowed a stream of dialogue through a loud-hailer, as the cymbals crashed wildly. It was the tale of a wandering yogi, who moved from cave to cave covered with rags, eating only nettle soup. He was a Tibetan peasant who, in the eleventh century, attained Buddhahood by practising tantric meditation while sitting in one cave for twelve years. The monk spoke of Milarepa's magical powers, of how he had walked through rock, flown in the sky, eaten stone. Then more monks came on, dressed as a deer, a dog and a hunter to perform the Deer Dance. The monk bellowed louder into the speaker, telling the story of the deer that dropped exhausted at Milarepa's feet one day while he was meditating in a cave in Nepal. It was pursued by a hunting dog that gave up its chase and lay down quietly. Then the hunter arrived and was converted by the holy man. The hunter spread Milarepa's fame throughout the land of Nepal.

Then they took us to see the holy cave. Long ago, it had been the lair of the last tiger in the area and a place of worship. It was how the town had acquired its name, for Tugsung means 'tiger's lair'. We walked up the other side of the hill past temples with rows of painted prayer wheels, turning each one and muttering, ' Om mani padme hum, as they creaked and rattled on their axes. Small wooden hutches stood on stilts in the stream to our left and Tsedup explained that they were also prayer wheels, driven by the water. Soon we came to a tall cliff, surrounded by pines that sighed and rustled in the drizzly air. At the foot of the cliff, hundreds of ndashung speared the ground in a thick cluster and we realised that we had reached the tiger's lair. All around the bottom of the cliff were recesses containing tsa tsa, small triangular clay icons, a few inches high, depicting the Buddha, formed from a bronze mould and sun-dried. Around these were piles of mani stones, rocks that pilgrims had carved with sacred syllables. The white rock face was covered with the same brightly coloured mantras: huge 'om' symbols scrawled like sacred graffiti. We squirmed into the cave mouth, only about a foot high, and ducked under the low crags, into the damp blackness. Someone lit a match and the flame cast eerie shadows around the walls of the deep, low cave. It felt strange to be inside the lair of a fierce beast and even though I knew it had been empty for a long time, I still felt the hairs on the back of my neck quiver.