Tim and Sam... ...will be out of the office until further notice.

Train T22 left for Xi'an on a cold, clear morning from an almost deserted Lhasa station. We both felt sad to be leaving Tibet and would have happily spent more time exploring a country that we both count as one of the highlights of the trip. It was certainly a fascinating place, with perhaps the friendliest and most resilient people we have ever come across. However, the impacts of the Chinese invasion are all too clear, and painful to observe. It was strange to be in a place where we were not free to move as we wished and could not talk freely with the people we met. We are safely out of big brother's intense gaze now and it would be all to easy to slide into a lengthy polemic, but I shall resist the urge.

The train ride back over the high altitude Qinghai-Tibet plateau was stunning. We had passed through this dream-like desert in the night on our way up to Lhasa but this time we traversed it in daylight hours. Along the way we were treated to sightings of wild ass, antelope, yaks and a tremendous frozen lake in which the water had expanded, pushing great slabs of broken, blue ice into a wall along its shores. While the railway is a further nail in the coffin for Tibet and should probably not have been built, you have to take your hat off to the Chinese for completing what must be one of the most implausible civil engineering projects ever undertaken. Some of the facts and figures listed over the speaker in our carriage beggared belief. It also relayed some other nuggets of information: heaters were installed in the portaloos so that the construction workers could go to the toilet at night without getting a cold bum, and during its construction no worker died of "plateau disease" or the plague. Thank god for that.

During the journey the train passed through some of central China's poorest provinces. The scenery was bordering on post apocalyptic: a deeply scarred landscape of endless brown terraces punctuated with trogloditic dwellings and belching factory chimneys. These were places that we were very happy to let pass by the window. After 36 hours we arrived in Xi'an, an ancient city that is home to the terracotta warriors and a bustling muslim quarter. The ancient has, of course, been either bulldozed or rebuilt but we had only a couple of days there and it was a pleasant enough place to pass the time. Having had our fill of dynastic history and mutton kebabs we spent our last few hours wandering the markets. Sam got rather over excited in the fake handbag stalls and there is a container load of knock offs working its way to the UK, that is unless HM Customs and Excise decide they look too fishy.

We battled our way through a scene of quite extraordinary chaos at Xi'an station and boarded train Z20 for Beijing. Given that there were only eight or so trains leaving Xi'an that night it was unclear what the thousands people outside the station were queueing for, but the train ride was a good one and we arrived in the capital on a bright and crisp morning. We visited Beijing in 2005 and saw the major sites, so this time we had a few days to relax and explore the less touristed areas. A highlight was a day spent at 798, a sprawling area of modern art galleries and workshops based in a disused, german industrial facility to the north east of the city. Much of the art was a little obvious, for example legions of Mickey Mouse characters battling with Chinese Lions and banks of Mao iconography, but there were some genuinely interesting pieces and we even wandered into the studio of the Gao Brothers and saw them at work. All in all a very new-China experience and a breath of fresh air after months of peering at pagodas and monasteries.

Time had come to leave China and start on the journey home. We woke before dawn and caught the first tube train to Beijing Station where we spent a grim hour in the malodourous waiting room. The Chinese government have made a concerted effort to convince Beijing residents to stop spitting ahead of the Olympics, but people haven't really taken it to heart. Stepping over the puddles of phlegm and piles of half eaten food we boarded train K23 for Ulan Baatar, Mongolia. Our carriage was decorated in an appealingly 1980s style: blue seats, red tubular steel fixtures, polyester anti-macassars and a frilly table cloth. Signs in cyrillic script gave an immediate feeling of having left the Orient and stepped into Soviet Central Asia. The other passengers on the train were mostly Mongolians, a handsome and tough looking bunch who were in high spirits and much better behaved than some of the passengers we have shared our journey with recently. The train headed north, at times giving good views of the Great Wall before heading through the plains of Inner Mongolia to Erlian, at the Mongolian border. Soviet rail roads use a different track gauge to the rest of the world so at this point, as well as pass through immigration, the train has to be moved into a shed to have the bogeys changed. It was late and this all took a long time. Having decided to stay on the train and try to sleep we were treated to two hours of banging, clunking and violent shunting. One particularly heavy thump sent the thermos tumbling off the table onto Sam's head, providing a rude awakening and causing her to nearly fall out of bed. The other thing we hadn't considered was that they had lock all the toilets so that the mechanics wouldn't get a nasty shower of filth as they worked. As a result of that and a few cans of Harbin lager we were both rather uncomfortable by the time we finally got rolling into Mongolia. Sleep came easily and the next morning we woke up trundling through a vast and beautiful wilderness of brown grasslands, sparsely populated by nomadic herdsmen living in traditional felt tents (gers). Winters are harsh in Mongolia, the average temperature in January is -26C and from the train we saw huge, black vultures picking over the carcasses of animals that had not made it through the long, cold months. By mid-afternoon the smoke stacks of Ulan Baatar pulled into view.

Ulan Bataar (UB) is not a pretty place, but it has surprised us both by being much more cosmopolitan than we had expected. Several free and fair democratic elections since the fall of communism in 1990 has given the Mongolian goverment access to a great deal of foreign aid from the west. Ties with Germany are particularly evident on the streets of UB, schnitzels and pilseners abound and the wurst are piled high in the state supermarket. We have been here almost a week now and have split the time between UB and the nearby Terelj National Park where we have been camping in a ger, hiking, peering at big Bactrian camels and charging around on horses. OK, trotting on ponies might be more accurate but in our minds we were Ghengis Khan striking out for Hungary.

The journey home is all falling into place. Tomorrow we leave for Irkutsk and Lake Baikal, Siberia. Sam is keen that we go dog sledding on the frozen lake, let's hope it works out better than the paragliding!