China is marking "Serf's Emancipation Day", a new public holiday commemorating what it calls the overturning of the feudal hierarchy system in Tibet 50 years ago.
Chinese authorities have compared the end of the Dalai Lama's rule in Tibet to Abraham Lincoln's emancipation of slaves in the US.
Celebrations on Saturday in the Tibetan capital of Lhasa were being prepared in secret, although they were to be nationally televised.
Marking the occasion, the Chinese-appointed Panchen Lama, who Beijing says is Tibet's second-highest ranking spiritual leader, praised China's communist rule of the territory.
"The freedom of the Tibetan people to inherit their ethnic and cultural heritage and their freedom of religion are protected by law," he said. "Religious culture has been respected, protected and passed down."
"The effects are more powerful than words. Only with the Chinese Communist Party could we have those who were serfs get human freedom and dignity."
Old Tibet 'misery'
The celebration began on Friday with testimonies about the misery of life in old Tibet.
But the effort to promote the anniversary has injected new tensions into the relationship between the government and Tibetan minorities and underscored the disparity between the way Chinese and Tibetans view their history.
Tibetan communities erupted in violent protests against Chinese rule last year, drawing a swift clampdown by paramilitary forces that have remained in place.
Security has been further tightened in recent weeks because of the March anniversary of the Dalai Lama's exile, which also marks a failed three-year revolt against Chinese rule that ended in 1959.
March 28 marks the date when Beijing ended the revolt and placed Tibet under its direct rule.
Meanwhile, in the Indian hill town of Dharamsala, Tibetan exiles staged protests on Saturday to mark the 50th anniversary of what they termed Chinese "repression" in Tibet.
"More than 500 protesters gathered at the town's main bus square and released balloons with messages of hope and solidarity with Tibetans in Tibet who continue to suffer under Chinese occupation," Tenzin Choeying, a member of a Tibetan youth organisation, said.
The protesters staged a street play followed by a march.
The protest organisers plan to hold a candlelight vigil in the evening, followed by a screening of film footage smuggled out of Tibet that showed violence being done against Tibetans, Choeying said.