The principle of non-violence is central to Buddhist teachings, but in Sri Lanka some Buddhist monks are being accused of stirring up hostility towards other faiths and ethnic minorities. Their hard line is causing increasing concern.
The small temple in the suburbs of Colombo is quiet. An image of the Buddha is surrounded with purple and white lotus flowers. Smaller Buddhas line the walls.
But upstairs, a burly monk in a bright orange robe holds forth - for this is one of the main offices of a hard-line Buddhist organisation, the Bodu Bala Sena or Buddhist Power Force (BBS).
The peaceful precepts for which Buddhism is widely known barely figure in his words. Instead, the monk, Galagoda Aththe Gnanasara Thero, talks of his Buddhism in terms of race. Most Buddhists here are ethnically Sinhalese, and Sinhalese make up three-quarters of the island's population.
"This country belongs to the Sinhalese, and it is the Sinhalese who built up its civilisation, culture and settlements. The white people created all the problems," says Gnanasara Thero angrily.
He says the country was destroyed by the British colonialists, and its current problems are also the work of what he calls "outsiders". By that he means Tamils and Muslims.
In fact, while a minority of the Tamils did indeed come from India as tea plantation workers, most of them, and most of the Muslims, are as Sri Lankan as the Sinhalese, with centuries-old roots here.
"We are trying to... go back to the country of the Sinhalese," says Gnanasara Thero. "Until we correct this, we are going to fight."
This firebrand strain of Buddhism is not new to Sri Lanka. A key Buddhist revivalist figure of the early 20th Century, Anagarika Dharmapala, was less than complimentary about non-Sinhalese people. He held that the "Aryan Sinhalese" had made the island into Paradise which was then destroyed by Christianity and polytheism. He targeted Muslims saying they had "by Shylockian methods" thrived at the expense of the "sons of the soil".
And later, in 1959 Prime Minister SWRD Bandaranaike was assassinated by a Buddhist monk - the circumstances were murky but one contentious issue was the government's failure to do enough to ensure the rights of the Sinhala people.
The long war against the Tamil Tigers - a violent rebel group purporting to speak for the Tamil minority - brought the hard-line Buddhists into their own once more. Portraying the war as a mission to protect the Sinhalese and Buddhism, in 2004 nine monks were elected to parliament on a nationalist platform. And it was from the monks' main party that Gnanasara Thero later broke away, in time forming the BBS. It is now the most prominent of several organisations sharing a similar ideology.
Since 2012, the BBS has embraced direct action, following the example of other like-minded groups. It raided Muslim-owned slaughter-houses claiming, incorrectly, that they were breaking the law. Members demonstrated outside a law college alleging, again incorrectly, that exam results were being distorted in favour of Muslims.
Now that a Tamil adversary has been defeated, Muslims seem to be these nationalists' main target, along with evangelical Christians whom they accuse of deceitfully and cunningly converting people away from Buddhism.
But can the BBS be called violent? "Whenever there is something wrong done by a Buddhist monk everything [is blamed on] us because of our popularity," says BBS spokesman Dilantha Withanage.
"BBS is not a terror organisation, BBS is not promoting violence against anyone... but we are against certain things." He cites threats by Islamic State to declare the whole of Asia a Muslim realm.
Time and again he and his colleague bracket the word "Muslim" together with the word "extremist".
They are not the only Sinhalese who express discomfort at a visible rise in Muslim social conservatism in Sri Lanka. More women are covering up than before and in parts of the country Saudi-influenced Wahabi Muslims are jostling with more liberal ones.
Yet there is no evidence of violent extremism among Sri Lankan Muslims. Rather, they have been at the receiving end of attacks from other parts of society.
In the small town of Aluthgama last June, three people died in clashes that started when the BBS and other Buddhist monks led an anti-Muslim rally in a Muslim area. At the time, I met Muslim families whose homes and shops had been burnt and utterly destroyed, and who were cowering in schools as temporary refugees.
Moderate Buddhists have also been targeted by hard-line ones.
Last year Rev Wathareka Vijitha Thero was abducted, rendered unconscious, tied up and forcibly circumcised - he says this was meant as a gesture of ridicule because he had worked for closer cooperation between Buddhists and Muslims.
He believes Buddhist monks - he doesn't know who or whether they were aligned with any particular group - were responsible.
In a separate case, a few weeks earlier, Vijitha Thero had held a news conference to highlight the grievances of the Muslim community - the gathering was broken up by the BBS. Gnanasara had hurled insults and threatened him: "If you are involved in this type of stupid treachery again, you will be taken and put in the Mahaweli River," he said.
The reference to the Mahaweli is significant - there was a left wing insurrection against the Sri Lankan government in 1989 - it's estimated 60,000 people disappeared and many dead bodies were dumped in the river.
Another country where fierce Buddhism has recently made headlines is Myanmar, formerly known as Burma. A Buddhist faction there, the 969 movement, is known for strident anti-Muslim campaigns that have triggered widespread violence.
Its leader, Shin Wirathu, was recently invited to Sri Lanka by the BBS. Both organisations say that even if Buddhism predominates in their own countries, overall it is under threat. "We want to protect it, therefore we signed a memorandum of understanding on forming alliances in the Asian region," says Withanage.
In January, Sri Lanka unexpectedly elected a new president, Maithripala Sirisena. He told me that "everybody knows" who gave rise to the BBS - implying that it was the administration of his predecessor, Mahinda Rajapaksa. The previous government was, at least, strongly supportive of the organisation.
And the group thrived because the rule of law had broken down, according to the new minister for Buddhist affairs, Karu Jayasuriya. He has told me that the BBS will be reined in. On Tuesday, Gnanasara Thero was arrested for taking part in an unauthorised demonstration but later freed on bail. Thus far, the new government - which, like the old one, includes a strongly Buddhist nationalist party - seems timid about taking on the men in orange.
Of all the moral precepts instilled in Buddhist monks the promise not to kill comes first, and the principle of non-violence is arguably more central to Buddhism than any other major religion. So why have monks been using hate speech against Muslims and joining mobs that have left dozens dead?
This is happening in two countries separated by well over 1,000 miles of Indian Ocean - Burma and Sri Lanka. It is puzzling because neither country is facing an Islamist militant threat. Muslims in both places are a generally peaceable and small minority.
In Sri Lanka, the issue of halal slaughter has been a flashpoint. Led by monks, members of the Bodu Bala Sena - the Buddhist Brigade - hold rallies, call for direct action and the boycotting of Muslim businesses, and rail against the size of Muslim families.
While no Muslims have been killed in Sri Lanka, the Burmese situation is far more serious. Here the antagonism is spearheaded by the 969 group, led by a monk, Ashin Wirathu, who was jailed in 2003 for inciting religious hatred. Released in 2012, he has referred to himself bizarrely as "the Burmese Bin Laden".
March saw an outbreak of mob violence directed against Muslims in the town of Meiktila, in central Burma, which left at least 40 dead.
Tellingly, the violence began in a gold shop. The movements in both countries exploit a sense of economic grievance - a religious minority is used as the scapegoat for the frustrated aspirations of the majority.
On Tuesday, Buddhist mobs attacked mosques and burned more than 70 homes in Oakkan, north of Rangoon, after a Muslim girl on a bicycle collided with a monk. One person died and nine were injured.
But aren't Buddhist monks meant to be the good guys of religion?
Aggressive thoughts are inimical to all Buddhist teachings. Buddhism even comes equipped with a practical way to eliminate them. Through meditation the distinction between your feelings and those of others should begin to dissolve, while your compassion for all living things grows.
Of course, there is a strong strain of pacifism in Christian teachings too: "Love your enemies and pray for those who persecute you," were the words of Jesus in the Sermon on the Mount.
But however any religion starts out, sooner or later it enters into a Faustian pact with state power. Buddhist monks looked to kings, the ultimate wielders of violence, for the support, patronage and order that only they could provide. Kings looked to monks to provide the popular legitimacy that only such a high moral vision can confer.
The result can seem ironic. If you have a strong sense of the overriding moral superiority of your worldview, then the need to protect and advance it can seem the most important duty of all.
Christian crusaders, Islamist militants, or the leaders of "freedom-loving nations", all justify what they see as necessary violence in the name of a higher good. Buddhist rulers and monks have been no exception.
So, historically, Buddhism has been no more a religion of peace than Christianity.
One of the most famous kings in Sri Lankan history is Dutugamanu, whose unification of the island in the 2nd Century BC is related in an important chronicle, the Mahavamsa.
It says that he placed a Buddhist relic in his spear and took 500 monks with him along to war against a non-Buddhist king.
He destroyed his opponents. After the bloodshed, some enlightened ones consoled him that the slain "were like animals; you will make the Buddha's faith shine".
Burmese rulers, known as "kings of righteousness", justified wars in the name of what they called true Buddhist doctrine.
In Japan, many samurai were devotees of Zen Buddhism and various arguments sustained them - killing a man about to commit a dreadful crime was an act of compassion, for example. Such reasoning surfaced again when Japan mobilised for World War II.
Buddhism took a leading role in the nationalist movements that emerged as Burma and Sri Lanka sought to throw off the yoke of the British Empire. Occasionally this spilled out into violence. In 1930s Rangoon, amid resorts to direct action, monks knifed four Europeans.
More importantly, many came to feel Buddhism was integral to their national identity - and the position of minorities in these newly independent nations was an uncomfortable one.
In 1983, Sri Lanka's ethnic tensions broke out into civil war. Following anti-Tamil pogroms, separatist Tamil groups in the north and east of the island sought to break away from the Sinhalese majority government.
During the war, the worst violence against Sri Lankan Muslims came at the hands of the Tamil rebels. But after the fighting came to a bloody end with the defeat of the rebels in 2009, it seems that majority communal passions have found a new target in the Muslim minority.
In Burma, monks wielded their moral authority to challenge the military junta and argue for democracy in the Saffron Revolution of 2007. Peaceful protest was the main weapon of choice this time, and monks paid with their lives.
Now some monks are using their moral authority to serve a quite different end. They may be a minority, but the 500,000-strong monkhood, which includes many deposited in monasteries as children to escape poverty or as orphans, certainly has its fair share of angry young men.
The exact nature of the relationship between the Buddhist extremists and the ruling parties in both countries is unclear.
Sri Lanka's powerful Defence Secretary Gotabhaya Rajapaksa was guest of honour at the opening of a Buddhist Brigade training school, and referred to the monks as those who "protect our country, religion and race".
But the anti-Muslim message seems to have struck a chord with parts of the population.
Even though they form a majority in both countries, many Buddhists share a sense that their nations must be unified and that their religion is under threat.
The global climate is crucial. People believe radical Islam to be at the centre of the many of the most violent conflicts around the world. They feel they are at the receiving end of conversion drives by the much more evangelical monotheistic faiths. And they feel that if other religions are going to get tough, they had better follow suit.
Alan Strathern is a fellow in History at Brasenose College, Oxford and author of Kingship and Conversion in Sixteenth-Century Sri Lanka: Portuguese Imperialism in a Buddhist Land