In the fourth and final instalment of his series on Islam in South East Asia, Roger Hardy asks where this important region is heading.
My journey has taken me through Malaysia, southern Thailand and Indonesia, with short stops in Bangkok, Manila and Singapore.
Does South-east Asia offer a model for the rest of the Muslim world?
It is a region of great energy, colour and diversity.
Some Muslims look to it as a possible role model - living proof that Islam and modernity are compatible.
So, can South East Asia fulfil its potential?
It seems to me it faces three main challenges.
First, its age-old religious harmony is now under threat from a new and radical form of Islam which has entered the region from outside.
The Bali nightclub bombing, which killed more than 200 people in 2002, was a rude wake-up call.
Rohan Gunaratna, one of the region's foremost security experts, says the bombings were the result of a partnership forged by al-Qaeda and a local group called Jemaah Islamiah, or JI.
Al-Qaeda had identified two of the region's characteristics - its large Muslim communities and its lax security - and ruthlessly exploited them.
"This was very fertile ground for al-Qaeda to plant its seed," Mr Gunaratna said.
After the Bali bombings, Indonesia came under fire for not cracking down harder on extremists - and for not outlawing JI.
Responding to the charge, Indonesia's new defence minister, Juwono Sudarsono, told me that outsiders should keep their voices down.
Shrill criticism from outside, he warned, played into the hands of the extremists.
Governments in the region are acutely aware they are engaged in a battle for Muslim hearts and minds.
Angry at America
So who's winning that battle?
The moderates are being weakened, and the radicals strengthened, by a tide of anti-Americanism that is sweeping the Muslim world.
South East Asia is no exception - and this, it seems to me, is the region's second big challenge.
I watched students chanting angry slogans outside the US embassy in the Indonesian capital, Jakarta.
They were protesting at US policy on an issue thousands of miles away in the Middle East - the Palestine problem.
And then, of course, there's Iraq.
"George Bush has been successful in alienating the Muslim world by occupying Iraq," one of Indonesia's best-known and most moderate Muslim leaders, Amien Rais, told me.
Even the swift and generous American response to December's earthquake and tsunami in South East Asia did little to redeem its image.
"I think the West wants to believe that the huge aid effort would automatically transform the negative image that some countries, particularly the United States, have in the region," says Sidney Jones, South East Asia specialist with the Brussels-based International Crisis Group.
"But it doesn't work that way. It's not that simple."
In other words, there's no quick fix. The causes of anti-Americanism are deep-rooted.
The limits of freedom
But one of the region's most thoughtful Muslims intellectuals, Anwar Ibrahim, warns that an obsession with America may be blinding the region to problems nearer home.
He was once Malaysia's deputy prime minister - but fell out with the country's former leader Mahathir Mohamed, and only recently emerged from six years in jail.
"The assumption of many Muslims is that all of the evils are because of the crimes and oppression and imperialism - all associated with the United States," he said.
"And they overlook the corruption, the authoritarian rule, the oppression by Muslim tyrants and dictators in [their own] communities."
The southern Philippines has witnessed violent clashes between troops and Muslim rebels
This is a part of the world where it takes guts to speak out against corruption and the abuse of human rights.
These issues, taken together, form the region's third big challenge.
In a hotel in the Malaysian capital, Kuala Lumpur, I watched a biting satire on corrupt government minister which made the audience rock with laughter.
"I don't take bribes - I take gifts," one actor screeched.
Everywhere I went in South East Asia, people lamented the prevalence of corruption, nepotism and "money politics".
The satirical show is astonishingly outspoken.
But this is a private function, held behind closed doors - nothing remotely as daring ever appears on Malaysian TV or radio.
Even in a country which presents itself as the progressive face of the Muslim world, freedom has well-defined limits.
Problems and potential
South East Asia's modernising Muslim societies still have some tough problems to solve.
Democracy is fragile and corruption widespread.
Conflicts involving Muslim minorities in the southern Philippines - and now in southern Thailand too - are blighting the region's prospects.
And the strength of Islamic extremism is not always acknowledged.
A de facto ceasefire has been in place since the tsunami in the mainly-Muslim province of Aceh
But if the challenges are great, so is the potential.
This is a region with an obvious thirst for progress and democracy.
It is a region where economic growth has been impressive - and where, for the most part, religious and cultural tolerance still prevail.
A role model for other Muslim nations?
I'd put it another way.
Muslims in the heartlands of the Islamic world surely have something to learn from their brothers and sisters in the east.
Roger Hardy's programme on the future of the region - the fourth in a four-part series, "Islam's Furthest Frontier" - is broadcast on the BBC World Service on 28 February.