Some 3,000 years ago, the House of Zhou overthrew the Shang dynasty in the battle of Muye and became the new ruler of ancient China. To justify its rule, the Duke of Zhou came up with the concept of the Mandate of Heaven, which holds that the divinity would unseat a bad ruler and bestow its mandate to a virtuous one. But the new king, whose legitimacy came from heaven, must have good conduct for it to continue endorsing his status as the rightful ruler. "Heaven has torn the mandate from the Shang state and passed it to us. It will allow us to rule only if we carry on King Wen's [the first Zhou king] virtuous conduct," he said, according to the Book of Documents, one of the Five Classics of ancient Chinese literature. READ MORE: China's top graft-buster breaks taboo by discussing Communist Party's 'legitimacy' Throughout Chinese history, new dynasties overthrew old ones and a successful revolt was interpreted as evidence that divine approval had passed onto a successive dynasty, who heaven appointed as the new, legitimate ruler. In July 1945, four years before the Communist Party defeated the Kuomintang regime, politician Huang Yanpei from the progressive China Democratic League travelled to the party base at Yan'an . He met Mao Zedong and asked whether Mao thought the party could break the pattern of the rises and falls of regimes that dominated Chinese history. Mao reportedly said: "We have found the new path... it is called democracy." After the party seized power, however, it turned to one-party rule. Its legitimacy has been repeatedly brought into question throughout its six-decade rule, especially during political upheavals such as the disastrous Great Leap Forward and the Cultural Revolution. And it is an issue that has continued to dog the leaders even to this day. Taboo broken Last month, Wang Qishan , one of the seven most powerful men in the party, broke a long-standing taboo by openly discussing the issue of the party's legitimacy. The top official in charge of the party's anti-corruption drive told some 60 foreign dignitaries at the Party and World Dialogue 2015, a conference in Beijing, that in order to be accountable to its people, the party must "govern with strictness". "The party's legitimacy arises from history and is determined by popular support, it is the people's choice," he was quoted by Xinhua news agency as saying. "For things to work in China, we have to see whether the people are happy or not, satisfied or not, whether they would approve [of our work]." For years, the word "legitimacy" was taboo. Discussion on the issue was forbidden as officials feared it would raise doubts among the people about the party's ruling position and lead to calls for democratic elections. But political scientists say the party has often mixed up "legality" and "legitimacy" and usually adopts the narrow sense of the term "legitimacy" as meaning "lawful" and not the sense as understood in Western political science that a regime needs the consent of the governed, or democratic accountability. It's like with a kidnapped bride; you can't say because I'm good to her, it's a legitimate marriage Hu Ping, U.S.-based commentator "Wang and his colleagues believe that the regime has a right to rule under the philosophy of Marxism, which says that the regime represents the interests of the people as decided by the outcome of the revolution in 1949," said Andrew Nathan, a political science professor at Columbia University. "He believes that this mandate does not have to be constantly renewed because it is a verdict of history. "[They think:] We won the revolution, we are in power, we intend not to relinquish that power, and in order to stay in power we have to attack corruption. The meaning of legitimacy within that official discourse is closed and circular, not something open to inquiry." New term, old concept Veteran journalist Ching Cheong said Wang was "using a modern term to package old party concepts" but his message had not departed from the party's long-held narrative. "[He thinks] the centralised authoritarian rule comes from history and culture. It's a time-honoured system, so there is no need to change," he said. Perry Link, a sinologist at the University of California, Riverside, said Mao used two different standards to claim legitimacy for the party in the early days. One was the support of the "masses" at the time of its victory over the Kuomintang in 1949, "as if the Chinese people 'voted' en masse - one time only", he said. The other was in Mao's own words: "Political power comes out of the barrel of a gun." Political power comes out of the barrel of a gun Mao Zedong "'I am legitimate because I won by force'," Link said. "The [party] doesn't want to acknowledge using this standard - even though, even today, it still uses it." Political scientists say even though Communist leaders did not use the term "legitimacy" before, the issue was never far from their minds. Before taking power, the Communists criticised the ruling Kuomintang for dictatorship and lacking the mandate of the people. A commentary in Xinhua Daily newspaper - a Communist Party mouthpiece - on February 17, 1945, headlined: "Democracy and legitimacy" said "Legitimacy means one has to conform to democratic decisions and to conform to people's will." An excerpt from the Selected Works of Mao Zedong published in Dalian in 1946, published a quote attributed to him: "A government that is not elected by the people, how can it claim to be representing the country?" The first constitution of the Communist Party in 1954 said: "All power belongs to the people". Mao also repeatedly emphasised this: "Who gave us our power? … The labouring masses who make up 90 per cent of the population." Legitimacy crisis However, along with people's loss of faith in the Communist ideology after the tumultuous years of Mao's rule, the party suffered a legitimacy crisis. Its early promise of democracy never materialised and disastrous political movements such as the Cultural Revolution alienated even those who once trusted the party. With paramount leader Deng Xiaoping's reform and opening, the party adopted a pragmatic strategy of "performance legitimacy". So long as the government can accomplish goals such as economic growth, social stability, or national strength, it will retain its legitimacy, it believes. When China was reeling from the disastrous Mao era, Deng said if the party did not implement reforms, it would lose its "membership of the earth", showing his concern that a regime would suffer a legitimacy crisis if it did not satisfy people's needs. Former president Hu Jintao said in a party plenum in 2008 that the party's ruling status was not to be taken for granted. "What we had in the past doesn't mean we have it now, what we have now doesn't mean we'll have it forever," he said. When Xi Jinping came to power as party chief in 2012, he warned rampant corruption would lead to "the party and the country being ruined". On a recent US trip, Xi said: "If we cannot solve problems and let them get worse, the people will not trust and support us." If we cannot solve problems and let them get worse, the people will not trust and support us Xi Jinping For the party to hang onto its mandate given by history, as well as to retain the people's support, current leaders believe the party must pursue the anti-corruption campaign and bring party cadres into line, scholars say. "To govern the country, we must first govern the party and we must carry this out with strictness," said Xi in the US. "We spare no efforts to tackle corruption...this is what the people want." Nathan said the party believed that, to defend its historical role as the legitimate ruler of China, the party must not be seen to be weak. "[To them], history is a class struggle, not a dinner party... Of course, enemies are undermining you all the time, so you have to keep your ruling instrument [the party] sharp, and that requires congyan zhidang [governing the party with strictness]," he said. Retired political science professor Joseph Cheng, formerly with the City University of Hong Kong, said the Communist Party had been using a formula of economic growth, social security and good governance to win hearts and minds. To prove to its people the party can deliver performance, the authorities set an annual GDP growth target of around 7 or 8 per cent, it launched a comprehensive reform of its health-care system and other social services such as pension, and to prove it was a good governor, the party launched an anti-corruption campaign and promised to “govern with strictness” and to rule the country by law. Also, the Communist Party has pulled out all the stops to quash viable alternatives to the regime, Cheng said, targeting not only fledgling political parties, but the civil society at large, nipping in the bud the development of any groups – be it NGOs or unofficial churches -- that could pose a threat to its rule. The lack of alternatives has convinced ordinary Chinese that only the Communist Party is competent enough to rule China, and that without the party, the nation would descend into chaos, which would be detrimental to their welfare. Balancing act Zhu Yuchao, a political scientist at the University of Regina, Canada, said that by resorting to "ruling with strictness", the party was playing a precarious "balancing game". "On the one hand, they're striking at corruption. On the other hand, they are attacking the liberal and pro-Western camps," he said. Scholars warn it is risky for a regime to rest its legitimacy solely on performance. In the absence of a shared ideology or a democratic process to allow people to choose their government, "performance legitimacy" was a source of potential political crisis, said Professor Zhao Dingxin, a political sociologist at the University of Chicago. He explained that while economic growth, improved social security as well as the high-profile anti-corruption campaign had lent credentials to the Communist Party for now, these could not be depended on forever. "If the state becomes unable to live up to popular expectations, the government and regime will be in crisis," wrote Zhao in 2009. In a democracy, grievances can be allayed by a change of government, yet "the current Chinese state offers no such alternative", he wrote. "Because the state relies heavily on its performance, any challenge to the moral and economic performance of top officials or state policies directly challenges the regime's legitimacy," he said. Zhu predicted the governing crisis would only get worse. The road ahead will only get narrower... there is no social cohesion so they can only use nationalism to unite people Zhu Yuchao "The road ahead will only get narrower... there is no social cohesion so they can only use nationalism to unite people. And there is a lack of [common] ideology so it will only get harder to rule," Zhu said. US-based political commentator Hu Ping, who won a seat in a district People's Congress in Beijing in free elections in 1980 when China was experimenting with limited democracy, believes "performance legitimacy" is a flawed concept. "Whether you're doing well or not, if you're not legitimate, you're not legitimate," he said. "Only when people can vote, then the Communist Party can be legitimate. "It's like with a kidnapped bride, you can't say because I'm good to her, it's a legitimate marriage," he said. Serious challenges Zhao warned the regime would face "serious challenges" and the possibility of a revolution could not be ruled out if it did not shift its primary basis of legitimacy to a more durable basis. He said a great deal of social discontent stemmed from ordinary people being dissatisfied with the government. Giving people the possibility of an alternative government would dissuade opposition to the regime, he said. Although there are concerns that even when authoritarian regimes are brought down, their transitions to democracy are not always smooth, and may even lead to more political instability. Joseph Cheng said that was all the more reason to cultivate a civil society and allow the people's congresses to criticise the government. If the [party] could make some top down, gradual reform, that would be the least costly option Professor Joseph Cheng "No one would expect a direct election of the state president in two years' time, but you need to make a start," he said. "If the [party] could make some top down, gradual reform, that would be the least costly option." Analysts said even if China was unwilling to go as far as allowing multi-party democracy, it would be wise to build a more durable basis of legitimacy by allowing freedom of speech and press and implementing rule of law and an independent judiciary so ordinary people could hold the government accountable and have access to justice. Zhao said the party should allow its members to genuinely nominate and vote for their representatives. "You don't necessarily have to have Western style democracy, but you need a procedure that is endorsed by most people to give your leaders legitimacy," Zhao said.