Jerko shared the family name, Kambo-Wasser as he was Amnye's illegitimate brother. The two had the same father. Ama-lo-lun knew about it, but it didn't seem to have been a problem for her. That kind of nocturnal liaison was not uncommon in the grassland. The Kambo-Wasser lineage was centuries old and their ancestors had origins in Kham, the province south of Amdo. The people of Kham were notoriously fearsome warriors of gargantuan stature, which explained Jerko's appearance. He was the tallest man in the tribe, with enormous square shoulders and a square jaw. His son, Gabo, was the strongest man, a prize-winning wrestler. The hallmark of a Kambo-Wasser man was his shoulders, which Tsedup had inherited, although Amnye was of a muscular but slighter build, more like Ama-lo-lun's family.

Outside Jerko's home, we joined the rest of the tribe. The lama and his retinue were hidden from our view within the dark confines of the tent, although the front flap had been raised and we could see some magenta-robed monks sipping tea. Jerko's family had laid out low wooden tables, which were overflowing with plates of momos, meat, apples, sweets, soft drinks and Ama-lo-lun's golden bread. The guests sat cross-legged on tufted Tibetan rugs, decorated with elaborate patterns, and I could just make out the golden glow of the butter lamps and the thankas they had hung on the sides of the tent. Outside the tent entrance they had prepared a throne, which was covered in silk cloth, for the old lama to sit on when he gave his blessings. Around me, the crowd mumbled in anticipation. The young girls wore elaborate headdresses that cascaded down their backs in a shower of coral, turquoise and amber. They had donned their best silk shirts with stiff gold brocade designs especially for the occasion and stood in a group, giggling and whispering, shyly nibbling the tips of their fingers. The old women cooed their satisfaction with my traditional costume and took my hand now and again, squeezing it affectionately. 'Amdo Namma,' they said gently, looking up at me with kind eyes.

The sun was growing fierce in the cloudless sky. The prairie lay scorched, the iridescence of the summer flowers lessening now to patches of yellow and lilac here and there. The Machu river shone back at the sky, the same pure blue. A raven looped lethargically above my head and made for the craggy heights of the mountains in the distance. I stayed close to Sirmo and watched for clues about protocol. Most people had begun to prostrate. I watched Shermo Donker push her palms together, then touch her forehead, her throat and her heart. Then she lay prone on the grass, her face buried in the dry stems for a moment before she rose and repeated the action. She was paying homage to the lama by practising the Buddhist form of obeisance. He was the embodiment of Buddha-body, speech and mind; the superior object of prostration. He was a sacred teacher, who had made a vow to serve all sentient beings and through his own actions could demonstrate the Buddha's teaching and give the Buddha's blessing.

Now, even the old men and women of the tribe were stretched out humbly before the empty throne, rising and falling like a Mexican wave. I felt self-conscious. I wasn't a Buddhist, but I had a great respect for their beliefs, and just as Tsedup had never stood up in church when everyone else was kneeling to pray, I wanted to honour this code of conduct. I had never been fit, however, so I was in trouble by the fifth prostration. Flushed of face and panting I was forced to stop, while next to me Tsedup's octogenarian grandmother was still going strong. I had due cause to feel inadequate – but, then, she was driven by a profound sense of devotion. I was not. She awaited the appearance of the sacred old man with all the eagerness of a child.

Except that he was a child. When he finally emerged from the tent, I was shocked to discover that the venerable lama was no more than five years old. He was dwarfed by his entourage of monks, who ushered him to his throne, lowering their heads in respect. His head was freshly shaved, his body draped in layers of miniature yellow and magenta robes, and when he climbed up on to his throne, his tiny Tibetan boots dangled over the edge of his seat. He gazed impassively at the throng before him and squinted in the midday glare. As the monks began chanting their prayer, we were all made to form an orderly line to receive the lama's blessing. One by one, the tribe approached him, bowing in supplication, holding the kadaks in their outstretched arms. He touched each of their heads and placed the scarf around their necks. I had been shocked when I met the thirteen-year-old lama Jarsung in Labrang, but nothing had prepared me for this extraordinary event. I was just as perplexed to see him as he would be to see me.

As I approached him I wondered what on earth he would think of me. Five-year-old children here usually stared and pointed when they first saw me but, of course, that would be an inappropriately extravagant display for such a sacred being, even if he had wanted to show his surprise. As I got nearer, it was impossible to keep my head lower than his as he was so small. I knew it was forbidden, but I was curious to look into his eyes, to see what lay within that face. As his tiny hand touched my head in blessing, I chanced a glimpse. He sat inert, staring with the intelligence of a scientist at my yellow hair. Like Jarsung, he had a seriousness about him that betrayed his inner self. His child's body was just a shell. I felt unnerved, as if he had the power to look into my soul.

He placed my kadak delicately around my neck, and in that moment I experienced an almost tangible sense of the magic and mystery of this place that I had come to love. I felt distanced, unable to understand it, as if the country itself defied being fully understood. It was a place of the unknown, of the fantastic, the impossible; a strange sanctum, whose very landscape was riddled with symbolism and whose holy men possessed superhuman powers. I looked away and moved on obediently, collecting my knotted protection cord, shugndot, from the monk at his side, as the lama bestowed the next Buddha blessing. Free of their religious obligations, the small children were now frolicking and rucking in the grass, splashing in the stream, falling in dung, shouting and laughing, hitting and pinching. Sirmo and I chided them as we walked back to the tent, but as I took one last look at the holy child climbing into his jeep, which was full of butter, I was happy at their wild freedom.

There was a feeling of elation in the tribe after the blessing, like the post-Communion camaraderie of a Christian congregation. There had been a washing of the soul by a 'wave of grace'; for that is what the word blessing, or shinlab, means in Tibetan. I watched the nomads return to their tents and the lunch-time milking.

That day I had witnessed their devotion to Buddhism, not in a monastery but at home. It was remarkable to have been outside, under the blistering sun and the dome of the sky and to have been part of their worship. I had seen evidence of their shamanic practices before, but this had been different. For me, that day revealed the nomads' piety, humility and their veneration of the lama, the symbol of Buddha.

In Amdo, the Buddhist deity predominantly worshipped is Lhamo. She is depicted with a fierce blue face and riding a mule. Amnye had explained that one could pray to her in a manner different from the practice of 'calling upon' the spirit powers of the earth and sky. In the mind of the nomad, Lhamo may be helpful after death, which none of the shamanic gods are. Equally, Chenrezik, the bodhisattva of compassion, may assist after death: his role is to delay his own entrance into nirvana – the ultimate Buddha state, which precludes all possibilities of reincarnation – until every sentient being has been released from the wheel of rebirth to accompany him. I had heard his mantra ' Om mani padme hum' muttered everywhere, as a means of supplication for his blessing. Indeed, the Dalai Lama is his incarnation: 'He who gazes upon the suffering of the world with tears in his eyes.'