In 2002, events occurred in Gujarat in western India which led many to wonder whether Hinduism - the religion practised by over 80% of Indians - is developing a new and more militant face.
That February, a Muslim mob attacked a train carrying Hindu pilgrims near the town of Godhra in Gujarat state. Nearly 60 Hindus were burnt alive.
The riots left 1,000 dead - mostly Muslims
In retaliation, mobs of Hindus attacked members of the Muslim minority across Gujarat state in the weeks that followed.
More than 1,000 people were killed, most of them Muslim. Some estimates put the riots toll at 2,000.
The Gujarat carnage was the worst religious violence India had seen in years.
There were allegations that the attacks on the minority community were carefully-orchestrated - and that members of the state's government, the Hindu-nationalist Bharatiya Janata Party (BJP), played a key role in the rioting.
Similar accusations were made against other organisations in the loose family of Hindu-nationalist groups known as the Sangh Parivar.
These claims have all been strenuously denied by the BJP and its associated groups.
But now, nearly two years after the riots erupted, is it possible to tell whether Gujarat is recovering from its trauma - and to find out what role, if any, the Hindu-nationalists really played?
Is a new and more aggressive form of Hinduism emerging in India. If so, what would the implications be for Gujarat, for India as a whole, and for Hindus throughout the world?
Fear and mistrust
Mohammed Irfan is a resident of Khanpur, a slum district of Ahmedabad, Gujarat's largest city.
The area has a mixed population. Impoverished Muslims live alongside Dalits - the poorest section of Hindu society.
Baddrunnissa says her business is struggling
In 2002, Khanpur saw Hindu-Muslim violence flare up, leaving a legacy of fear and mistrust.
And Mr Irfan, an auto-rickshaw driver, says life is still tough for local Muslims.
It is only in the last two months, he says, that he has been able to find enough work to earn a living.
He won't enter areas that are mainly Hindu anymore. He says two Muslim colleagues who did so recently were badly beaten up.
Mr Irfan's neighbour, Baddrunnissa, is a middle-aged lady who runs a roadside kiosk selling sweets and soft drinks.
She says her business is struggling.
"Before the riots, I used to sell about 500-600 rupees worth of goods a day, but now it's only 40 rupees worth. And I fear we may be attacked any time from anywhere."
Another neighbour, a grocer named Liaqat, told a similar story.
"My business is down to about a quarter of what it was, as Hindus don't come into my shop to buy goods," Liaqat says.
"I think it's deliberate, because they don't want Muslims to prosper, even in small businesses."
One man who's been working hard to help rehabilitate riot victims is Sherif Khan Pathan, a leading Muslim businessman.
Sherif Khan Pathan - security fears have driven people apart
He is based in the middle-class Muslim neighbourhood of Shah-e-Alam. Its bustling bazaars and thriving shops are a stark contrast to the poverty and deprivation of Khanpur.
But he too has a grim tale to tell.
"This was traditionally a mixed area, with both Hindus and Muslims. But after the riots, it's become completely polarised as Hindus have moved out," Sherif says.
"When the two communities live together, they learn about each other's traditions and customs. But concern about security has driven people apart."
He blames the Gujarat state government for the violence of 2002, as do many other Muslims - and moderate Hindus.
It seems as if there are two parallel histories of the recent events in Gujarat.
Sherif Khan Pathan and many others believe that the BJP state government, possibly fearful that it might lose power, exploited the attack on the Hindus on the train at Godhra and unleashed mobs on to exposed Muslim communities.
The other version - put forward by Hindu nationalists themselves - is very different.
They hold that if there was any conspiracy, it was the train attack against Hindus. And they argue that the scale of the subsequent riots has been exaggerated, and so too have the reports of damage to communal relations.
But for two local Hindus, there is no doubt about the damage done to Ahmedabad - both in terms of the loss of lives and property, and the loss of trust.
At the city's Government College, one young lecturer, Neeta Khurana, talks about the mood in the city still being tense.
"College students, like most human beings, are generally not interested in what the two communities are doing. We live our life. But there are vested interests which blow things out of proportion, so that they end up in heated passions," Neeta Khurana says.
"And religion of course is something which really affects your passions. In both communities, politics and money are things which motivate people to any extent."
Her colleague Urmesh Mehta is sceptical about the Gujarati authorities' attempts to portray the communal violence as a thing of the past.
"I find the situation still precarious. They are trying very hard to show the world that we are doing well and we are coming out of it. But they have not succeeded."
Elsewhere in Ahmedabad's Hindu community, very different opinions are voiced about the riots.
Dilip Trivedi is the Gujarat state leader of the Vishwa Hindu Parishad (VHP) - which describes itself a cultural body aiming to unite Hindus around the world.
It's closely linked to the ruling BJP, and its critics accuse it of inciting hatred of minorities, particularly Muslims.
Mr Trivedi denies this.
But he says the assaults on Muslims by Hindus in 2002 were inevitable -
"The attack on the train was made by the Muslims. And every action has its own reaction."
He rejects the charge that the VHP sees all India's Muslims as traitors.
"We don't say all the Muslims are not loyal to India. The majority are loyal to India," Mr Trivedi says.
"We believe that all Muslims are not terrorists - but all the terrorists are Muslims. And that is why it is for the Muslims to establish their loyalty."
As well as the BJP and the VHP, there's another member of the Sangh Parivar which has been accused of playing a key role in the carnage of 2002.
The Rashtriya Swayamsevak Sangh (RSS) was founded in the 1920s, and is committed to making India a "truly Hindu" nation.
It blames India's former Muslim rulers, as well as European colonial empires, for many of the country's present problems - such as poverty and backwardness.
RSS members at their morning drill
It has millions of members who meet at sunrise every day across the country.
We attended one such ceremony, at about 0600 in a park in a middle-class suburb of Ahmedabad.
About 30 RSS members clad in khaki shorts, drawn mostly from the professional classes, went through a range of chants, salutes and exercises, including fighting with lathis - long wooden sticks.
The meeting was led by the RSS president in Gujarat, Amrit Kadiwala.
He explained the RSS view of Hinduism as the fundamental identity of all Indians.
"Hindu is a very wide term. It is the symbol of nationality. So even the Muslims of this country, they are Hindu Muslims. We consider India our motherland, and give some thoughts as to what should be the ideals in our life and how we can be useful to society."
That seemed disingenuous, given the RSS's emphasis on drill, ritual and exercise - particularly the sparring with lathis. So why does Dr Kadiwala think such combat-training is necessary?
"For physical strength," he says.
"Every person should be strong enough. We want to get people united, and physical strength is necessary for any nation, any society. It doesn't mean we're militant."
But Dr. Kadiwala's reassuring words are unlikely to persuade those critics of the RSS who see it as a para-military movement bent on turning India into a Hindu-dominated state in which the rights of minorities will be curtailed.
Rahul Sarnaik will have two more reports on fears over Hindu extremism, one from the wealthy Indian communities of the United States, and the other from the Indian state of Rajasthan.