(CNN) -- Tensions between Tibetans and Chinese authorities that exploded into violence in Lhasa this week are nothing new, with longstanding troubles turning the region into a tinderbox where anger regularly comes to the surface.
Chinese tourists look on as a Tibetan prostrates himself at a monastery in Tibet.
Since Chinese troops invaded the region in the 1950s -- pushing its spiritual leader, the Dalai Lama, into exile -- there has been little love lost between Tibetans and their rulers.
While Chinese authorities have opened up the region to tourism and trade in recent years, keen to showcase their tolerance of Buddhist tradition and their investment, there has been no let up in Beijing's strict controls.
Likewise, the antipathy felt by ordinary Tibetans towards China and the ethnic Han Chinese who have arrived in droves as part of an official trans-migration policy has shown no sign of abating.
I visited Lhasa in August 2005, as China was preparing to mark the 40th anniversary of the founding of the Tibet Autonomous Region -- the authority by which it controls the Himalayan territory.
Just as the current anniversary of a failed 1959 uprising has triggered unrest, the significance of the date was clearly stoking tensions during my visit.
Chinese authorities were in an ebullient spirit, draping celebratory flags across Lhasa's main thoroughfares and playing Chinese pop songs over loudspeakers in front of the sacred Potala Palace.
Adding to the triumphant mood was the nearing completion of the Bejing-Lhasa railway -- without doubt an incredible feat of engineering, but seen by many as an attempt to increase China's stranglehold on the region.
In the main Barkhor market square, where devout Tibetan Buddhists prostrate themselves before holy shrines, crowds of Chinese tourists swarmed through market stalls, haggling over prices with undisguised contempt for local traders.
Despite the artificial holiday atmosphere, it was clear that Chinese authorities were keeping a very close eye on proceedings. Police stood in doorways and closed circuit television cameras peered down from every rooftop.
When, at one point, a fight broke out, the police reaction was swift and overwhelming. Cars raced in, disgorging dozens of uniformed officers, who arrested those involved.
Apparently undeterred by this, a local teacher approached me to vent his frustration, asking me what I thought about China and Tibet.
I replied with bland comments about the beautiful landscape; according to guide books, Chinese police are not above posing as ordinary Tibetans or even monks to lure tourists into inappropriate behavior.
His reply was unequivocal, and given the level of surveillance, surprisingly bold.
"I hate China. I hate the Chinese, they have ruined this country," he said, before drifting off into the crowds.
As the date of the anniversary neared, Chinese authorities tightened their controls, shuttering businesses that arranged tours for Westerners and closing off monasteries and areas beyond Lhasa.
Before the restrictions were in place, we managed to make a five-day overland trip to China's camp at the base of Mount Everest.
Here, at the end of a remote road up which China intends to carry the Olympic torch ahead of this year's Beijing Games in an attempt to stamp its mark on one of the region's most recognizable landmarks, was an emphatic expression of Tibetan sentiment daubed on the mountainside.
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