No signs along the long and dusty mountain road point the way to the Cultural Revolution museum complex.

And this year, no commemoration for the millions of victims of Mao Zedong's mayhem was held on the anniversary of its start.

The mountaintop museum on the outskirts of Shantou chronicles an uncomfortable chapter of history that China's ruling Communist Party would rather forget.

Neighbour was pitted against neighbour, child against parent, and the Red Guard student movement was tasked with purging ideological "foes", often bloodily, as Mao forcefully reasserted his power over the party and the country following the disaster of his Great Leap Forward and the subsequent famine.

"We came to this Cultural Revolution museum to cherish the memory of the victims, our compatriots," said Liu Jingyi, 41, a business owner who brought his son and daughter.

"I talk to my children about the events of the past, and I tell them that in the future, they must conduct themselves with integrity and be upright, honest people," he said.

The Communist Party officially declared Mao "70 percent right and 30 percent wrong", and has said the Cultural Revolution dealt China "the most severe setback and the heaviest losses" since the foundation of the People's Republic in 1949.

But it has never allowed a full reckoning of the turmoil that took place between 1966 and 1976.

"I feel quite ignorant about history. I came here to try to understand things better," said a lone 20-year-old student surnamed Chen, perusing inscriptions of hundreds of crimes from the era: "Capitalism". "False Marxism". "False leftist, true rightist".

The main exhibition hall contains a day-by-day account of the decade of violence and ideological frenzy, alongside hundreds of images of Mao and other party leaders, public shamings, beatings and killings.

Two vast red columns proclaim: "On heaven and earth, this calamitous history exists here alone. In all the world, what's most important is the ability to judge right from wrong."

- 'Dead souls' -

The privately funded museum was founded -- with neither support nor outright opposition from Communist authorities -- by Peng Qi'an, the former deputy mayor of Shantou, on China's southern coast.

Peng's brother, a teacher, was beaten to death and Peng, now 83, listed for execution. It was never carried out, for reasons unknown.

The sprawling complex includes long black walls bearing the names of several thousand victims, and since 2006 hundreds of their relatives have gathered every August 8, the anniversary of the Communist Party Central Committee's decision to launch the Cultural Revolution.

China's official Xinhua news agency previewed last year's ceremony and quoted Peng saying: "I promised the dead souls we would mourn them on this particular date every year, even if I have to climb up the mountain to their graves in a wheelchair."

But this month's event was called off at the last minute, apparently under pressure from the authorities. Shantou officials could not be reached for comment, but Peng stayed away from the museum, and declined to be interviewed for this article.

Under President Xi Jinping -- whose chosen themes of anti-corruption and frugality echo some of Mao's edicts -- China has tightened its limits on freedom of expression, jailing human rights lawyers, journalists and activists.

In recent months official media have publicised the confessions of several former Red Guards, including Song Binbin, a powerful general's daughter who participated in one of the first and most notorious killings of a teacher.

But such candour has strict limits.

The ruling party has allowed general criticism of the Cultural Revolution "because that's the official stance", said Barry Sautman, a professor of social science at the Hong Kong University of Science and Technology.

Any discussion that touched the roles of specific leaders "would be a big problem", he said.

"Politicians do what they do best, which is exercise power. If it's to protect themselves, they'll be sure to do so."

More than 70 local residents killed during the Cultural Revolution are buried near the museum, thousands of others were persecuted, and many more are still haunted by the events of the time.

On the morning of the anniversary a few visitors defied the cancellation to attend.

A 72-year-old retiree, who declined to give his name for fear of retribution, said that in pre-Communist China his grandfather had been involved in legal proceedings that saw several people in Shantou executed.

During the Cultural Revolution, "the responsibility for this was placed on the head of my father" and he was killed, he said, determined to speak out but his quiet tone revealing his anxiety.

The family were declared "landowners" -- the worst of the Communist Party's "five black categories" of enemies.

"China today is still very factionalised," he went on, tears welling in his eyes. "Some things are still not very clear. I worry that I might be harmed once again."