I spent three days in Kashgar, the scene of yesterday’s attack on some Chinese police, and where I took this photo in its famous and busy market, a couple of months ago.

It’s a city with a long and glorious history - first as one of the key trading points on the ’silk road’ with a famous international trading market - and then in the nineteenth century as a key location in the ‘Great Game’, the epic power struggle between the British in India and Russia, for control of Central Asia. The opening of a Russian consulate there nearly provoked full-scale war between Britain and Russia (in the end it didn’t survive long as a consulate, but you can still stay in the building, as one person I travelled with this year did).

Kashgar now finds itself in the ‘Xinjiang Uighur Autonomous Region’ - a huge and sparsely populated province which forms the whole north west of the modern state of China. But although it lies east of the massive Tian Shan range of mountains which forms China’s western boundary, bringing it naturally geographically into China, its people are not Chinese and have much more in common with the central Asian peoples west of the Tian Shan. The Uighurs of this region are ethnically central Asian, have been Muslim for many centuries, and speak a language, Uighur, closer to Uzbek, and which is written in the Arabic script. At various points in history they have attempted to assert their central Asian identity, most recently around the time of the second world war, when the ‘Republic of East Turkestan’ was declared (Turkestan being the whole huge central Asian territory of the peoples of Turkic descent going back to Genghis Khan and beyond).

Ethnically, they are clearly right that they belong to Turkestan rather than China.

But equally clearly the Chinese state, like any great power, is not at all keen to have unstable breakaway regions outside its control sitting on its borders. This is hardly something new from the post-1949 communist period in China - emperors two thousand kilometres away in China proper have long sought to have this region and these people under their control.

And so in many ways the Uighurs in Xinjiang (the Chinese name for the province, which I understand means something like ‘border province’) pose a similar challenge to their Tibetan neighbours.

And the Chinese government’s response bears some similarity to the Tibetan issue. In particular there has been a large influx of Han Chinese into Xinjiang in recent years - so large indeed that, as in Tibet, it is significantly changing the ethnic composition of the populace. This has been particularly strong since oil was discovered and drilling has intensified - particularly further north of Kashgar, a day’s train ride the other side of the Taklamaklan desert in the regional capital Urumqi (imagine having an entire desert between two cities in the same region! - a reminder of just how huge China’s distances are).

There have also clearly been attempts by the government to manage down the Uighur identity and insist it is part of one China: it is formally in the same time zone as Beijing, for example - plainly absurd when it is so far away, and it is roundly ignored locally by everyone except government officials. Most people operate on an unofficial time zone of their own, two hours behind Beijing time. But the Chinese government has also recognised the usefulness of some acknowledgement of their separate identity: Islam and mosques are not at all banned, and the Uighur language, in its Arabic script, is not banned and is indeed an official language, appearing alongside Chinese on signs.

Nevertheless some Uighurs say that there are systematic attempts by the Chinese government slowly to take over and eclipse the Uighur identity, including oppression of the kind that goes on in Tibet. This is the root cause of the separatist movement apparently behind yesterday’s incident. Uighur nationalists will say that the major difference between them and Tibet is, as someone (not in Xinjiang) put it to me, the Uighurs “don’t have the Dalai Lama doing their PR” - and therefore don’t have anything like the same international recognition that Tibet does. I have to say honestly that I don’t myself know enough about the situation to be able to judge how true this is - I was only there for three days!

Certainly Kashgar doesn’t feel like a city on edge or ill at ease - I had a fun time looking round its old streets, its mosques, famous markets and families out strolling and playing in the park on a warm summer’s Sunday afternoon.

The moment when you do realise how sensitive the situation is, is when you come to see close up just how literally Kashgar is ‘on the edge’ of China. The border post for the Torugart pass crossing into Kyrgyzstan is just an hour’s drive away, and that and the two hour drive further up to the actual pass and crossing is a militarised zone, fully equipped with soldiers with absolutely no sense of humour about, for example, foreigners who want to take photos (it’s a place to lock your camera deep in your bag, and take the memory card out first just in case they decide to confiscate your camera anyway!) On the day we went through, several of the border posts were holding memorial events for the many thousands of Chinese (the soldiers are all Chinese, not Uighur) killed the previous week in the earthquake in Sichuan. I haven’t been able to find out exactly where yesterday’s attack took place (the news reports I can find just say “near Kashgar”) but I can’t help wondering if it was at one of the remote checkpoints, up at 10,000 feet and in amongst the long caravan of heavy trucks coming down the road from Kyrgyzstan, that I travelled through and had my passport checked four times in fifty yards at, a few weeks ago.