By Jake Hooker www.ft.com

Korbanan, a Tajik girl with sleepy, blue eyes and a dark, freckled face, flips through a book of stories I've been reading along the old Silk Road. Though she can't understand them, the strange letters, printed round and black on rough white paper, seem to fill her with wonder. I understand her feeling.

Tashkorgan was my last stop on a trip through China's Xinjiang Uighur Autonomous Region, named after the 8m Turkic Muslims who live in the oases surrounding the Taklimakan desert. Tajiks, Kazaks, Uzbeks, Russians, Mongols and seven other non-Chinese ethnic minorities also live in Xinjiang, among the most culturally mystifying places in China.

I had started my journey two weeks earlier in Chengdu, the capital of Sichuan province. The sun set on emerald rice paddies and rose over fields of wheat. On the second morning of my train journey, we clipped past standing armies of sunflowers lifting their sleepy heads to the east.

The sand bars of the Yellow River and western end of the Great Wall seemed but whispers of Chinese civilisation, and later my mind was free to roam over the parched flats of the Gobi desert and the blowing dunes of the Taklimakan. After four days, I arrived in Kashgar.

China's introduction of white tile and concrete has done little to temper the sensual middle eastern flavour of this Uighur Mecca. Islam arrived in Kashgar from the Transcaspian Khanates of Khokand, Samarkand and Bukhara around AD950, when an exchange of crafts and ideas flourished along the Silk Road.

One feels this legacy walking the dusty lanes of Kashgar's old town, where mud-brick neighbourhood mosques snuggle beside glass shopfronts, and inside, beautiful girls in bright headscarves sew silk dresses by hand.

In Kashgar, the word 'bazaar' takes on fresh meaning. Every day, tens of thousands of traders flood the Kashgar international trade market of central and western Asia. Along Izlati Road, men with square skullcaps lean like dentists into the mouths of camels and sheep.

Bearded Uighur patricians sit in the sun eating crescents of dripping cantaloupe, and men on wooden donkey carts lash their way through the crowds, shouting "Bosh! Bosh!" - "Coming through! Coming through!"

I entered through a tunnel of shimmering silks. Inside, Uzbeks sold hand-woven carpets from Bukhara, and Uighurs everything from Hotanese jade to rubber soles and rat poison. Golden raisins came from the eastern oasis of Turpan, and spices such as cardamom, sapphire and paprika from Pakistan and India. I haggled for a handcrafted dagger from Yarkand, the hilt carved from yak horn and inlaid with mother-of-pearl.

The Chinese say Xinjiang has belonged to them since ancient times, when local Turkic and Mongol chieftains gave handicrafts to the Emperor as tribute. Though they built garrisons in the western regions as early as the first century AD, the Chinese didn't attempt to govern the area until the 18th century. Fifty years ago, few Chinese lived in Xinjiang. Today, they outnumber the Uighurs.

On my last night in Kashgar, I sipped cool sapphire tea under leafy poplar trees with a stocky Uighur named Abdullah. "The streets of Kashgar were once lined with peach trees," he said wistfully.

Before road and rail links, change rarely came from the east, as the distances were too great. In the Tang Dynasty (AD618-907), it took seven months to travel by camel caravan from the Chinese capital of Chang'an to Kashgar. The central Asian Kingdoms to the west were far closer.

Geography is the key to Xinjiang's ethnic diversity, a fact I discovered first-hand on a bus ride south to Tashkorgan, an isolated Chinese border town 100km north of Pakistan. Yellow muskmelons roll beneath our feet as we speed through the desert flats west of Kashgar. After climbing along the muddy torrent of the Ghez River, we stop at a customs checkpoint. The canyon remains in shade, but overhead the glaciers of 7,719-metre Mount Kongur flash like diamonds.

Then we emerge as if to a different world. Runnels from Kongur snake through the grasslands, and silver-grey sand dunes hug the horizon. Two-humped Bactrian camels loiter by the roadside, and Kyrgyz with flat, red faces watch their sheep and yaks grazing by their yurts.

We arrived in Tashkorgan after dark. Five clocks, "Beijing, London, New York, Urumqi and Ankara", hung in the lobby of the Traffic hotel, none of them working. After the bustle of Kashgar, the place seemed eerily silent. I slept in a stark, concrete room under heavy, cotton quilts. The temperature plunged by a season overnight.

The next morning, I strolled along the main street, past white statues of Tajik men wearing square hats. Megaphones tied to telephone poles blasted news and public service messages in a language that sounded like Persian. Next to the rusted skeleton of a Beijing Jeep, red Chinese characters painted on a wooden vestibule preached "Nurture the road, assure smooth access". In ancient times, the garrisons had been set up to do just that.

I ate lunch in a Sichuan restaurant where People's Liberation Army troops with green uniforms ate pork and smoked. Next door, two pretty Chinese girls waited behind the glass doors of the Sichuan Sisters Hair Parlour.

But Xinjiang is a region of oases, and Tashkorgan's main street was a rather small one. The town had no side streets, and in the surrounding countryside, no Chinese.

Just five minutes north of town, Tajik men with hard blue eyes and Iranian features harvested summer wheat. Walking that evening at the edge of town, I came to a small hill perched with crumbling mud-stone battlements. In the Uighur language, tash korgan means stone fortress, and the ruin I'd come to see dates from the late 13th century, when Kublai Khan's Mongols took China and central Asia by storm. To my delight, the fortress was empty and unguarded, and I scrambled up a stony slope to the top.

I'd come a long way, but others had come further. In the third century AD, pilgrims from India had trudged through this valley with news of a Brahmin named Sakyamuni. A thousand years later, Marco Polo described this very fortress in his Travels.

Above parapets rounded by wind and time, I can see in all directions. To the north, the snowy bowl of Mount Mustagh Ata floats above a skirt of clouds. To the south, the valley widens, a grey line disappearing towards the horizon - the road to Pakistan. Below, to the east, red and blue specks move about on the grasslands.

Korbanan drops her sickle to the ground when she sees me.

As her mother and father dump green armfuls into a wooden wheelbarrow, Korbanan and I sit on the ground and talk. She speaks beautiful Mandarin, and studies music in Kashgar.

"What instrument do you play?"

"Shou-feng-qin."

Stumped, I pass her my notebook, and she writes three square characters "hand, wind, string" next to her name, a squiggle of Persian. A harpist, I divine, and raise my left hand towards the sky, while wiggling the fingers of my right like a spider. She smiles.

The next morning I catch the bus back to Kashgar, but first I sit for a little while longer with Korbanan. My strangeness arouses her curiosity; her life of herding and music mine. As the sun dips over the sharp, treeless mountains separating China and Tajikistan, the long shadows of the ancient battlements creep toward us, seeming to fill this quiet valley with spirits.

Accommodations in Tashkorgan are very basic. Next to the bus station the Traffic Hotel has shared dorm rooms or doubles with private bath and hot water. The Ice Mountain Hotel and Pamir Hotel offer comparable alternatives just down the street.

In the evenings the open-air vendors beside the mustard minarets of Id Kah Mosque offer Uighur specialtiessuch as samsa (lamb and onion pockets baked inside a mud-lined oil drum), nokot (spicy chick-peas served cold with shredded carrots), gangpen (pilaf fried with lamb, squash, onions and red peppers in an enormous steel wok) and, my favourite, balyk (fried fish). When in doubt, succulent lamb kebabs and cantaloupe can be had on every corner.