Lhasa, Golmud, Xining, Lanzhou, Xian and Chongqing provide the scenes for a 49-hour first act in a train journey from Tibet to Hong Kong that lasts half a week - as in, 84 hours. En route you pass everything China has to offer: farms and factories, mountains, rivers and more farms and factories. And people. Spend 31/2 days on trains or in stations in mainland China and it begins to feel like you've rubbed shoulders and shared squat toilets with millions. The starting point is misleading: Lhasa's station is a gorgeous facility; that rare blend of modern and traditional architecture in China that seems like a bridge between generations instead of some twisted vision of the future. If you ride in a soft sleeper, the train is as comfortable as they come, replete with a flat-screen television, hotel-standard bedding and pedestal toilets with wooden seats in the relatively clean bathrooms. Passengers can also make use of an oxygen inhaler if the altitude makes them light-headed. When you're not watching Infernal Affairs on the TV, or chowing down on a 10-yuan lunchbox of surprisingly decent Sichuan cuisine, the ride is a pensive one. Darkness is a great equaliser, covering up poverty and the stark environment. As the train rolls in to a random Chinese town in Shaanxi province, with streetlights and neon hotel signs but little else, it feels like you are driving down a US interstate watching the Wal-Marts slip past. It's hard not to consider the significance of the route, with its implications for the people of Tibet and China as a whole. It seems tragically bizarre that every monastery in Tibet displays only photos of the Panchen Lama or previous Dalai Lamas. It's like imagining the Vatican without a single photo of Pope Benedict. And when the TV shows videos of Tibetan dancers performing for the railway's opening, it's troubling to recall that tens of thousands of Tibetans died in the 1950s during the Chinese occupation. On the complicated other hand, is Tibet viable without being part of China, or some other industrialising country? If not Chinese, then what better second language should Tibetan children be learning? And to return to the train, would Tibetans - most of whom will never be able to afford the plane ticket - rather make week-long bus rides to get to the nearest modern city? Ironically, the further from the remote highlands and the closer to the industrialised heartland the train gets, the dingier the stations become. Each has successively less shine and more people, and by the time you reach Chongqing - on a mid-summer's day - the pensiveness stops and the sweating begins. They don't call this one of China's four great ovens for nothing. After half a day soaking up the amenities of a Chinese metropolis (supermarket, internet, McDonald's), it's time to head south. There are direct trains from Chongqing to Guangzhou, but a slight detour takes travellers to the stunning terraced hills of southeast Guizhou province. In the rural hamlet of Leisha I refuel with beer and rice wine poured by old friends of the Miao ethnic minority to whom I taught English years ago. Most of them are teachers, paid 400 yuan a month to cram 60 students into an ill-equipped classroom in a school kilometres from the nearest paved road. Yet they adore karaoke and internet cafes, imploring visitors to sing the latest Jay Chou song or chat on QQ instant messenger. Twenty hours to Guangzhou is the next stage and the train-station signs are becoming more familiar. After Guangzhou, of course, is Shenzhen. Then Lowu. Looking back at the mainland across the Shenzhen River before taking the KCR (now part of MTR) and re-acquainting myself with efficiency and cleanliness, relief settles in. I am determined to take trains as far as possible and a tram could top off the journey. But after chugging through nearly 5,000km, standing around dozens of train stations in the dead of night, slurping down Styrofoam bowls of instant noodles, I give in at the Admiralty bus terminus, take the 590 to South Horizons and home. Getting there: Air China ( www.air-china.co.uk ) flies from Hong Kong to Lhasa via Chengdu.