While Tibetan exiles traditionally mark the failed 1959 uprising on March 10 with marches, people in Tibet have usually chosen more private forms of commemoration, says Anne Holmes, director of the Free Tibet Campaign in London.
This year, however, "they are aware that in the run-up to the Beijing Olympics, the media's and the world's eyes are on Tibet," she says, "They felt it was worth the risk of doing a lot more this year than they would normally dream of doing.
"Tibetans see this as a make or break year. This is the year when world attention is focused on China's human rights record," she adds.
This week's protests, which have spread to other Tibetan monasteries in the Qinghai region of China, will "bring the issue of China's presence in Tibet higher up the international agenda than it has been for a long time," says Ms. Holmes.
Historically, Tibetan Buddhist monks marked the Great Prayer Festival in March, until the festivities were banned by the Chinese authorities in 1989, following disturbances.
In recent years, says Tibet expert Robbie Barnett, who teaches at Columbia University in New York, only small groups of monks and nuns have demonstrated publicly. "This week is so significant because the monks have finally dared to test the system again by demonstrating in numbers," says professor Barnett. The Chinese police "have responded by not using lethal force and keeping people out of the city center," he says, in contrast to their use of firearms against monks in the 1980s, which sparked major protests by lay people.
After years of low-profile actions, monks are now protesting in large numbers because the Communist Party provincial boss, Zhang Qing Li, appointed 27 months ago, "seems to have brought the most heavy-handed policy, replying to even the smallest protest as if it were a threat to the state and blaming the Dalai Lama for it," says Barnett.
Although demonstrators in Lhasa have chanted pro-independence slogans, the monks themselves have voiced very specific demands, according to reports from the city, and have staged sit-down protests lasting several hours while insisting that the police negotiate with them.
The monks are asking for the release of monks arrested this week and last October, for the withdrawal of police and Army troops from monasteries, and for the reinstatement of monks expelled from monasteries for failing "patriotic education" exams that require them to denounce the Dalai Lama, according to Barnett.
"I think they will get some of these demands," he predicts.