The Himalayas have often been at the centre of intense political and military activity. In the 19th Century, India and China could not agree where each other's territory began and ended. The British attempted to settle the squabble by drawing on the map a border which became known as the Inner Line.
Simon Worrall has just been to Tibet on an expedition inspired by the great 19th-Century British photographer, Samuel Bourne.
We cross The Inner Line at midday.
For more than 24 hours we have been winding our way up the Sutlej river valley towards the border between India and China.
A surly border guard checks our passports and permits.
On the other side of the road there is a group of Kinnauri women dressed in long wool skirts and pillbox-type caps made of grey or brown wool. They are squatting on the ground, waiting for a bus.
The guard spits and waves us on.
Sheltered from change
I am on my way to a Tibetan Buddhist monastery called Ki.
At 15,500 ft (4,724m) it is one of the highest monasteries in the world.
The Indians call this region "the land where you eat dust" and as we climb higher and higher I see why.
Vast slopes of cinnamon-coloured scree topped by teeth-like outcrops of rock claw at the sky.
Bourne was to the Himalayas what Ansel Adams was to the Rockies
The ground is dry as a bone, but we do not have to eat dust.
There are delicious mo-mo, Tibetan steamed dumplings, and thukpa, a soup made with fresh noodles, mutton and cabbage.
A thousand years ago, this bit of India was part of the powerful Tibetan kingdom of Guge.
The kings of Guge built monasteries like Ki to spread Tibetan Buddhism in the western Himalayas.
After the 1962 border war between India and China, the region was sealed behind The Inner Line, a militarised zone that straddles the border between the two countries... like a bee in amber.
This proved a blessing.
Protected from the ravages of the Chinese Communist Party on one side and "Hinduisation" on the other, this remote, sparsely-populated region has preserved a way of life and a spiritual legacy that is hard to find even in Tibet itself.
At Tabo, the oldest Buddhist monastery in the western Himalayas, I find frescoes as breathtakingly beautiful as Giotto's in the Capella degli Scrovegni in Padua. And in the courtyard a group of red-robed novices playing cricket.
A dream come true
The next day, as Ki appears in the distance, my heart skips a beat.
I have dreamed of this moment ever since seeing a photograph of the monastery taken by the great - and greatly undervalued - 19th-Century British photographer, Samuel Bourne.
Bourne was to the Himalayas what Ansel Adams was to the Rockies.
His journey to Ki, accompanied by 60 bearers - a cavalcade of yaks, sheep and goats, boxes of glass photographic plates and a large supply of Hennessy Brandy - was a three-month trek of epic proportions.
Ki is a Himalayan Mount Athos, a cluster of flat-roofed buildings perched on a pinnacle of rock that rises out of the valley floor like a needle.
Waiting to greet us is a tall, melancholy-looking young novice named Tsewang.
He wears battered sneakers and a threadbare blue anorak over his robes.
He shows us to our room: an eyrie the size of a ship's cabin at the very top of the monastery.
It is the abbot's room, explains Tsewang, but the abbot and most of the other the monks have already left for the winter.
Tsewang has to break the padlock to let us in.
In the corner, on an old tin trunk, is a makeshift "altar", a wooden plank covered in a green cloth decorated with photographs of the Dalai Lama.
Next to one of the pictures I notice a jar of Vicks Vapour Rub.
Butter tea and snow
Time moves slowly at Ki.
The arrival of a group of donkeys laden with sacks of barley, on our second day, is a major event.
We spend most of our time, cocooned in down jackets, hats and gloves, sitting round the woodstove with Tsewang drinking Tibetan butter tea, trying to keep warm.
We are almost at the same height as the summit of the Matterhorn.
Breathing is hard, like getting caught underwater without enough air.
The stove makes it worse. Every time the wind shifts, smoke belches into the room, sending us hacking and coughing onto the stone terrace outside.
We daren't stay long. Snow is already falling higher up the pass.
So at the end of the third day, we say goodbye to Tsewang and set off on a gruelling, overnight drive back to Shimla.
As we drop into the valley, I turn and look back. The outline of the monastery, perched on its pinnacle of rock, is just visible against the evening sky.
It is exactly the view taken by Samuel Bourne in 1866.
From Our Own Correspondent was broadcast on Saturday, 19 March, 2007 at 1130 BST on BBC Radio 4. Please check the programme schedules for World Service transmission times.