A couple of riots broke out in Singapore in 1964 - the first of which took place on July 21, which is today marked as Racial Harmony Day.
Amid rising communal tensions following the Malaysian general election in May that year, a procession celebrating Prophet Muhammad's birthday was disrupted by clashes between Chinese and Malays.
The first day of rioting saw four killed and 178 injured.
The authorities imposed night curfews island-wide and set up goodwill committees of community leaders to calm the situation.
But clashes continued through July, and by the time the situation calmed down in early August, 23 had died and 454 were injured.
The calm did not last long.
On Sept 2, 1964, fighting broke out after a Malay trishaw rider was found dead in Geylang Serai.
The fighting that lasted over a week left 13 dead and 106 injured.
In 1997, the Ministry of Education began marking July 21 as Racial Harmony Day. On this day, schools hold activities to teach students the importance of maintaining racial and religious harmony.
There is zero tolerance for racial incidents here, but once in a while, they happen and go viral.
In a Facebook post in May this year, Singaporean actor Shrey Bhargava alleged he was a target of racism during an audition for a Jack Neo movie.
In April last year, local bakery chain PrimaDeli apologised and sacked a staff member who allegedly made racist remarks to a candidate during a job interview.
In October 2012, the National Trades Union Congress fired assistant director of membership Amy Cheong, a 38-year-old Australian and Singapore permanent resident, over her expletive-filled racist rant on Facebook. Police also issued a stern warning to her in March 2013, after an investigation.
However, not all racial incidents that went viral have been negative.
In January this year, former senior parliamentary secretary Maidin Packer shared how Malay wedding guests at an HDB void deck in Pasir Ris stood to pay their respects to a passing Chinese funeral procession.
"This is so Singapore," he wrote on Facebook.
Terrorism has changed the face of racial harmony in Singapore.
The Sept 11, 2001 attacks on the United States killed nearly 3,000 people and injured more than 6,000.
In Singapore, the Internal Security Department (ISD) crippled a local cell of regional terror network Jemaah Islamiah (JI), arresting 13 members in December 2001 and 19 in August 2002.
The group wanted to create an Islamic State in the region, and was plotting to bomb foreign embassies and government buildings here.
After its plans here were foiled, the group staged the Bali bombings in October 2012 that killed more 200 people.
Although JI has been weakened, its ideology remains and radicals have pledged allegiance to terror group Islamic State in Iraq and Syria (ISIS).
In the past three years, the ISD has detected and detained 15 self-radicalised Singaporeans who were seduced by ISIS' propaganda, including some who were planning to travel overseas to fight.
The latest cases involved an infant care assistant, the first woman to be detained for radicalisation, and two auxiliary police officers.
The Harmony Centre is tucked within the premises of the modern-looking An-Nahdhah Mosque in heartland Bishan.
The centre houses artefacts and information about Islam, as well as other major religions in Singapore.
It also organises inter-faith programmes, such as dialogues with leaders from other religious groups.
Run by the Islamic Religious Council of Singapore (Muis), the centre was set up to promote a greater understanding of Islam and Muslims among Singapore's multiracial and multi-religious society.
Its programmes include talks and open houses, and it regularly hosts visitors from local groups and abroad.
When Prime Minister Lee Hsien Loong opened the centre on Oct 7, 2006, he said: "It aims to be a one-stop centre to promote inter-religious dialogue, and to explain the true teachings of Islam."
He added that its opening was "a significant step forward in continuing efforts to bring Singaporeans of different faiths closer together".
Race is one of the three key potential fault lines in Singapore.
The National Pledge starts with this sentence: "We, the citizens of Singapore, pledge ourselves as one united people, regardless of race, language or religion..."
It is a recognition that race, language and religion are forces that can divide Singaporeans.
Of the 3,408,900 Singapore citizens, 2,595,800 (76.1 per cent) are Chinese; 510,200 (15 per cent) are Malays; 253,300 (7.4 per cent) are Indians; and 49,700 (1.5 per cent), including Eurasians, are classified as "Others".
Although the Chinese are the overwhelming majority, the Singapore Constitution guarantees that all persons are equal before the law and that there shall be no discrimination on the basis of, among other things, race.
It also states that the Government has the responsibility to constantly care for the interests of racial and religious minorities.
The Constitution also recognises that the Malays have a "special position", because they are "the indigenous people of Singapore", and that the Government has a responsibility to safeguard their interests and language.
Several surveys in the past few years have shed light on Singaporeans' attitudes towards racial harmony.
In August last year, broadcaster Channel NewsAsia and the Institute of Policy Studies (IPS) - a think-tank - published a survey which found Singaporeans strongly support multiracialism and meritocracy.
But while nearly all of the 2,000 citizens polled said they respected people from all races and that all races should be treated equally, almost half recognised that racism could be a problem and were aware that a significant number are at least mildly racist.
The IPS also published a survey in 2014 which found that 16 per cent of 4,000 Singapore residents polled felt that racial prejudice had grown over the preceding five years, while 46.8 per cent said it had not changed.
These findings share a common thread: Singaporeans recognise that racism, in some form, still exists here, and should be countered.
Community confidence-building is a tool Singapore has consistently used to promote racial harmony.
An army of more than 38,000 volunteers recruited by the People's Association (PA) run activities that promote social cohesion and bonding in all the constituencies.
One such grassroots leader is Mr K. Gopal. The 66-year-old has experienced racial riots first-hand - the 1964 riots took place when he was 13 and living in the quarters of the Royal Air Force base in Changi. His father worked there as a technical officer.
"We were frightened," he said. "My parents did not allow me to go to school for several days."
He started volunteering with the PA in the late 1980s and has served on committees such as the residents' committee and citizens' consultative committee.
He is now the honorary chairman of the Nee Soon East Community Club Management Committee.
A grassroots leader helps promote bonding and builds trust among people living in the community, he said.
"The riots were violent and there was bloodshed. We cannot let it happen again."
Islamophobia is the dislike or fear of Islam, arising from prejudiced views against the religion.
Muslims here and abroad have been put under the spotlight each time terrorists abuse the faith and invoke its teachings to commit terror acts. And Islamic scholars and community leaders have consistently condemned terrorists who use Islam to justify their violent acts.
Singapore's top Islamic scholar, Mufti Fatris Bakaram, said in his Hari Raya Aidilfitri sermon last month that the faith respects local cultures, and the traditions and cultures in Singapore do not conflict with the Prophet's teachings.
Playing a key role in preventing Islamophobia from sinking its roots here are the Inter-Racial and Religious Confidence Circles (IRCC) in all constituencies here. These local-level, inter-faith groupings were set up to promote racial and religious harmony, including by getting people to better understand various faiths and their teachings.
Several government leaders have spoken up against Islamophobia recently. Prime Minister Lee Hsien Loong said last month that Islamophobia is as bad and unacceptable as radical terrorism, adding: "We have to make sure that none of that happens."
Affirmative action is a broad term to describe positive discrimination, or efforts to assist a group that has been under-represented in a particular role. The term has been used to describe changes to the Constitution to guarantee minority representation in the presidency. These will see this year's presidential election reserved for Malay candidates.
"There is an element of affirmative action in the approach," former Cabinet minister S. Dhanabalan said at a public hearing when the changes were being considered by a commission set up to review the elected presidency.
Some analysts have pointed out the pitfalls of such action. Institute of Policy Studies (IPS) deputy director Gillian Koh noted: "The moment you institute this, you are saying certain communities cannot make it and they require certain help."
Such affirmative action is uncommon in Singapore, and some see it as going against the principle of meritocracy. But others have said the move upholds the equally important principle of multiracialism.
IPS' Mathew Mathews says the same eligibility criteria apply to all candidates regardless of race, adding: "The reserved election serves to eliminate the possibility that racial biases may disadvantage minorities who are exceptionally qualified for the presidency."
Like race and religion, language can divide Singaporeans.
There are four official languages in Singapore - English, Chinese, Malay and Tamil.
English is the language of government administration. The laws are written in English. The primary language of instruction in schools is also English.
While there are four official languages, there is only one national language, which is Malay. The words of the National Anthem, Majulah Singapura, are in Malay.
The language issue crops up from time to time on the jobs front. While few employers now advertise that they want "Chinese employees", some jobseekers feel they use "Chinese-speaking employees" as a proxy.
The Tripartite Alliance for Fair and Progressive Employment Practices, the national anti-workplace discrimination watchdog, says employers should look at jobseekers' skills and state the reason why proficiency in a particular language is needed. For example, a Chinese, Malay or Tamil language teacher is needed to teach the subject in a pre-school centre.
More than 80 per cent of Singaporeans live in Housing Board flats. In 1989, the Government introduced an Ethnic Integration Policy (EIP) to prevent racial enclaves from emerging, by setting limits according to race on the proportion of flats in a block and a neighbourhood.
In 1989, the caps were set at:
•22 per cent of flats in a neighbourhood for Malays, and 25 per cent in each block;
•84 per cent of flats in a neighbourhood and 87 per cent in each block for Chinese;
•10 per cent in a neighbourhood and 13 per cent in each block for Indians and other minority groups.
In 2010, the caps for Indians and other minorities were raised to 12 per cent of flats in a neighbourhood and 15 per cent in each block.
Under the policy, owners are free to sell their flat to a buyer of any race, as long as the racial limits are kept.
The Government also introduced caps in 2010 on non-Malaysian permanent residents. They cannot occupy more than 5 per cent of flats in a neighbourhood and 8 per cent in a block.
The EIP is the Government's way of maintaining a balanced, multiracial mix in the community.
Observers and politicians have noted that Singapore is a small country and Singaporeans live in close proximity to one another. Friction, including between people of different races, cannot be avoided.
Institute of Policy Studies deputy director Gillian Koh wrote in The Straits Times last month: "Different groups and their practices bump into each other in the heartland, at work... When conflict arises, we can resort to taking or giving offence, or turn these incidents into opportunities to deepen understanding and strengthen cohesion."
The spirit of give-and-take also requires responsible religious leaders who are able to handle sensitive issues, noted Prime Minister Lee Hsien Loong in 2015. "From time to time, we will have prickly issues, we have incidents with a racial tinge.
"For example, when you are dealing with families where there have been conversions, where there have been inter-religious marriages, where there are children involved... It is very sensitive, emotions are up, everybody is already upset, and something like this comes along, it can easily become a problem.
"And so we have responsible religious leaders... they set the example, and so we have been able to have amicable, compromise solutions with a spirit of give-and-take."
Religion is a major potential fault line in Singapore.
Recognising that religion can divide Singaporeans, Parliament passed the Maintenance of Religious Harmony Bill in 1990.
When the proposed law was debated, then Home Affairs Minister S. Jayakumar said that it was "preventive" in nature. It was meant "to nip problems in the bud... to prevent matters from escalating and creating tensions, frictions and conflicts between different religious groups", he added.
The Act gives powers to the Government to issue restraining orders against any person who causes ill feelings between different religious groups. Those who violate the restraining orders may be fined or jailed, or both.
A Presidential Council for Religious Harmony was also set up to advise the Minister for Home Affairs on matters that affect religious harmony in Singapore.
The current 10-member council is chaired by former Supreme Court judge Goh Joon Seng.
Meritocracy has always been a key pillar of Singapore's policies.
The idea is that success is not tied to one's background, such as race, and opportunities are given to everyone to succeed on his own merits.
This idea is important for preserving racial harmony because it means that no racial group will be given special treatment and neither will any be put at a disadvantage.
But Dr Norshahril Saat, a fellow at the ISEAS-Yusof Ishak Institute, said in a commentary in The Straits Times last year that meritocracy in Singapore was not perfect.
The "abridged" version has ensured minority representation in Parliament and stabilised race relations.
Reserving the next presidential election for Malays was necessary to develop trust among the races, he added.
OnePeople.sg is the national body that promotes racial and religious harmony. It says on its website that it "champions racial harmony initiatives in Singapore".
Its current chairman is Dr Janil Puthucheary, Senior Minister of State for Education, and Communications and Information.
Its founding members are the People's Association, all five Community Development Councils and five ethnic-based self-help groups.
OnePeople.sg's predecessor was the Central Singapore Joint Social Service Centre set up in 1997 to coordinate the resources of the CDCs and self-help groups in reaching out to Singaporeans. The centre took on the role of promoting racial harmony in 2001, coordinating such activities with PA. It was renamed OnePeople.sg in 2007.
The organisation is particularly known for the month-long Orange Ribbon activities that it has organised every July since 2008 to promote racial harmony.
On Racial Harmony Day in July 2012, Prime Minister Lee Hsien Loong warned of new fault lines emerging in Singapore.
On top of race and religion, he highlighted rising tensions between citizens and new immigrants as a cause of worry.
His warning came at a time when anti-foreigner sentiments were rising and locals perceived new immigrants and foreigners as causing social problems and snatching jobs.
It was not just a one-way street. In September 2015, a 28-year-old Filipino nurse was sentenced to four months' jail for making xenophobic and inflammatory remarks about Singaporeans and lying to the police.
The most high-profile anti-foreigner case was arguably that of Singaporean Yang Kaiheng, 28, and his wife Ai Takagi, 24, an Australian of Japanese descent.
The couple, who were behind socio-political website The Real Singapore, were convicted under the Sedition Act last year for deliberately sowing discord between Singaporeans and foreigners through a series of articles on their website. Yang was sentenced to eight months' jail and Ai, 10 months.
Two weeks ago , the National Youth Council released the findings of a survey that the attitudes of young people towards other races and nationalities have improved.
Of the 3,531 young people aged between 15 and 34 polled, the percentage of those who have a close friend of a different race increased from 53 per cent in 2013, when the last survey was conducted, to 60 per cent last year, while those with a close friend of a different nationality also grew from 42 per cent to 45 per cent.
Dr Janil Puthucheary, chairman of OnePeople.sg, said the nature of what young people see as racial issues has also changed.
"No longer are we worried about race and race bias in terms of access to public services such as education, health and housing," said the Senior Minister of State for Education, and Communications and Information.
Their concerns have taken on an "aspirational tone", such as worrying whether they have friends of other races, he said.
"What they are worried about are issues like: 'Are they friendly to me? Do they make racist jokes? Do they have a stereotype? Do they see me for who I am?'," he added.
The idea of a code on religious harmony was first suggested by then Prime Minister Goh Chok Tong in October 2002, after the two waves of Jemaah Islamiah (JI) arrests in Singapore.
A team headed by then Minister of State Chan Soo Sen worked on the code. Leaders from various faiths were asked to take part.
The code was unveiled in June 2003 and read for the first time at the Racial Harmony Day celebrations a month later. It is now read in schools every year, on July 21.
The declaration says:
"We, the people in Singapore, declare that religious harmony is vital for peace, progress and prosperity in our multiracial and multi-religious Nation.
We resolve to strengthen religious harmony through mutual tolerance, confidence, respect, and understanding.
We shall always:
Recognise the secular nature of our State,
Promote cohesion within our society,
Respect each other's freedom of religion,
Grow our common space while respecting our diversity,
Foster inter-religious communications, and thereby ensure that religion will not be abused to create conflict and disharmony in Singapore."
For Racial Harmony Day, which started in schools 20 years ago, activities were held last Friday to mark the occasion.
At most schools, students donned ethnic clothes to represent diversity. Methodist Girls' School went a step further, however.
It tied up with the People's Association to conduct an art project for which students painted images of samsui women - migrant construction workers in the 1920s to 1940s - on wooden planks that were displayed at the school.
"Samsui women are among the pioneers who built Singapore," said art teacher Natasha Tay. "Pioneers like them also contributed to building racial harmony in Singapore."
Alison Lim, nine, who took part in the project, said: "I learnt the samsui women were resilient." She also learnt to include other races in her circle of friends.
The Primary 4 pupil said she had watched videos in class that showed racial riots of the past. "We were surprised that people were fighting then. It is so peaceful now."
When Racial Harmony Day was first observed at the Methodist Girls' School on July 21, 1997, Christina Loong was a 13-year-old Secondary 1 student there.
Fast forward 20 years. She is still in the same school, but she has since shed her school uniform. Instead of sitting at the back of the class facing the blackboard, she now stands in front of the class teaching history and social studies to Secondary 1 and 4 students.
Now 33, Ms Loong has a fuzzy memory of exactly what happened 20 years ago.
But she recalled watching a video of the racial riots in school. "We were horrified by what we saw," she said. "Most of us did not know about the riots until we learnt about them in class and watched the video."
The annual Racial Harmony Day remains relevant, she added.
"The students now are more aware of racial harmony - they have more sources of information and are better informed," said Ms Loong. "But it is still important to have a constant reminder of the importance of racial harmony."
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A version of this article appeared in the print edition of The Sunday Times on July 23, 2017, with the headline Racial Harmony Day in Singapore: 20 years on. Subscribe