Five hundred years ago she was a green, grassy virgin. Her villages are now swallowed beneath grey streets; her clogged veins littered with history. She wears her age heavily, but opens her embrace to poor and rich alike. Popularised by Monica Ali's novel Brick Lane, she is a fusion of rural Bangladesh and East End vigor. But this is only her latest incarnation. She has had many names; many faces.

Sandwiched between Spitalfields and Whitechapel, ‘Banglatown’ has been called the spiritual heart of the East End. Her story is more complex and multi-faceted than one novel might ever tell. Writers from Dickens to Wilde and Arthur Conan Doyle have been drawn here, setting their stories amidst the folds of her crime, dissent, and poverty.

This is where Jack the Ripper and the Kray Twins once roamed. Where Stalin and Trotsky shared a flat, and the suffragettes had their headquarters. Municipal socialism was born in the lanes around Hawksmoor's East End churches, whilst the fictional villain Fu Man Chu was said to reside among Limehouse's infamous opium dens.

Brick Lane and the surrounding East End are where generations of the poorest immigrants fetch up – whether 'lascar' sailors jumping ship from Sylhet or Ashkenazi Jews fleeing Russia's pogroms – to face tremendous discrimination and hardship. These new arrivals work in the sweatshop industries, clash with the indigenous population – like the Irish and Natives in Martin Scorsese's film, The Gangs of New York – before making the area their own, then finally moving on out.

Irish immigrants fought native English beneath these same skies, in the race riots of 1736. French Huguenot refugees melted into the London fabric, whilst Jewish gangs battled each other, before making way for the Sylhetis of Bangladesh. And now a new ripple has begun, with the arrival of East European and Somali migrants; a new breed of yuppies and 'arty' young whites on their tails. This history of struggle and change is even imprinted on the buildings, such as the former Huguenot chapel, then Methodist church, synagogue, and mosque on the corner of Brick Lane and Fournier Street.

Today the beat of Banglatown's heart is contained in the tongues of a hundred nations; her rhythm the call to prayer, mixing with the rough hip-hop of her sound systems. It is a place where worlds collide, with the City on its very doorstep and the shame of prostitutes on its streets. Teenage gangs stalk the estates. Drugs are taking hold amongst a nominally Muslim youth. Unemployment and overcrowding are high. Her synagogues are mostly silent, but there are still some signs of Jewish identity – like the stone masons at the entrance to Brick Lane itself – which speak of an age only recently past.

It is here that I have met my fellow author, the award-winning novelist Hari Kunzru, whose seminal work, The Impressionist, tells its own story of changing identity. He loves the area, he says: "I've lived in West, East, North and South London over the years, and I find myself increasingly drawn back to the East End". But there are other stories, too, if you look away from the curry houses and trendy bars which snake along Brick Lane's length. Into areas where the name Monica Ali is not well-liked.

From the yellowing bowels of Aldgate East tube, down the Roman-straight expanse of Whitechapel Road, you walk past the little park commemorating Altab Ali, the tailor murdered by white racists over two decades ago. Clothed in the sweat and grease of a late summer's day, past sullen pubs which seem to lean inwards, past Osborn Street which leads on to Brick Lane proper, within spitting distance of the ancient Whitechapel Bell Foundry, you approach the impressive, modern bulk of the East London Mosque.

On a Friday evening as dusk draws down, the streets and alleyways around the mosque – one of Britain's oldest, founded in 1910 – swarm with the faithful. Arab, Bangladeshi and African flow like a river into the great building. Behind it the old Fieldgate Street Great Synagogue is almost lost, swallowed by the rising steel skeleton of the new London Muslim Centre – the largest of its kind: a Muslim business centre, shopping mall and library – crafted to the side of the mosque. It is a mirror, almost, to the glittering shapes of the City skyscrapers and Docklands looming close by.

Surprisingly, mosque and synagogue share excellent relations. The mosque's chairman, Dr Muhammad Bari, a lean, neatly-dressed man who was once an officer in the Bangladesh Air Force (and is also deputy secretary of the Muslim Council of Great Britain), told me from inside his sweltering, whitewashed office: "Although we feel differently about the injustices on Palestine, in Islam we are asked to live peacefully with our neighbours. We're all people of The Book." During Yom Kippur, for example, all work was ceased on the London Muslim Centre out of respect for the Jewish festival.

Yet in our conversations, Dr Bari spoke at length of the identity crisis which has swamped the Bangladeshi population, driving a wedge between old and young. "People are opening up to the truth," he says. Placing a hand onto his trimmed beard, he adds that even the elders realise there's a drug problem.

Perhaps the first generation has looked too much to the past, to the old homeland, to traditional solutions and the advice of the village Imams to sort out the problems of today. That at least is what I have gleaned during conversations over sweet tea and Arab Cola in the cafés around Whitechapel. ("Some girl has problems, they threaten to send her back to Bangladesh and an arranged marriage".)

And it is here that a new identity is being forged in response. Followers of a progressive Islam that takes hold where the Salvation Army was born, in an East End which at one time or another has called itself home to religious radicals, from Levellers, Ranters, and Anabaptists, to Fifth Monarchy Men and Quakers.

Siraj Salekin is my guide into this world: into the real Brick Lane. Into the heart of Banglatown, part of the Islamic Umma – or worldwide community – that calls so powerfully among these troubled peoples. Siraj is one of the most impressive men I have met in my journeys into Islam: journeys that have taken me across North Africa and the Middle East. A passionate speaker with a soft, whiskered face and shining eyes, the 37-year-old graduate and father of five remembers the day he arrived in Britain. The day he moved to Brick Lane itself.

"I came here during the dustbin strike of Lord Callaghan," he laughs. "We took the taxi from the airport and I saw all the bins and I said I wanted to go back home, back to my green land! But I've been here ever since," he adds, "except for a short stint at Battersea College and even that felt like a journey for me."

Siraj is a modest man, falling into a fast, tripping speech when gripped by fervour. This speech slows and his voice takes on a tremble as he talks about the father who came to Britain but refused to become British; who eventually left to settle back in rural Sylhet and has now passed away.

"My dad was quite educated. He was a policeman in the British forces. He came before he got married, no after his marriage I think. He was in his late 20s I imagine..." His words falter. He looks away. "He used to say we had blood in every brick in this country. We sweated out back home in British factories, then we came here we did it again! This country became prosperous on our backs."

Siraj has made it his mission to understand his own background, travelling to Sylhet and interviewing all his relatives and their friends to build an impressive family tree. He also made a point to understand his own faith, twice completing the Hajj pilgrimage to Mecca. He has bound both together to make a documentary about the roots of the community. He shows it to those for whom a gang is the closest thing to family.

"There's a huge identity crisis with the youngsters here," Siraj admits. "I want to educate people. Often I find they don't know who they are. When they know who they are, they can stand on their two feet and feel proud." He shakes his head, recalling how Bengali "uncles and aunties" have been attacked and mugged by their own youth.

But things are changing. Holding his youngest daughter as we chat in the Vita Bar, a cold café run by a bearded Egyptian ("I won't eat out, my wife has better cooking!" Siraj confides) he details his achievements: leading 2,000 people in a human chain to protect the site next to the mosque from commercial development. From there, the community raised £6m (out of £10m) to build the new Muslim Centre. And as if that were not enough, he later takes me inside Mosque Towers, a mini-skyscraper which is the country's first all-Asian pensioners' home. He built that too. And helped create the Tower Hamlets Council of Mosques; set up a school attendance project; and initiated a series of mobile youth centres to travel around the densely populated, overcrowded estates, winning the government's coveted Beacon Status for Community Cohesion.

Picking a chilli – "real Bengali chilli, very hot" – from one of the house plants he so loves but says his wife despises, Siraj jibes that I should "revert" (convert) to Islam. "We are all born pure in the eyes of God," he tells me, smiling. I don't tell him about my visits to the pub opposite the mosque.

When we next meet, Siraj introduces me to Joe Ahmed-Dobson, the lightly-beared, youngest son of former government minister, Frank Dobson MP. Twenty-seven-year-old Joe is a revert. A West Ham fan, too, who takes his Bengali father-in-law to matches. Both Siraj and Joe are admirers of Tariq Ramadan's writings. Ramadan is the grandson of the founder of the Muslim Brotherhood in Egypt. He argues it is time to develop a more moderate, European Islam, one that looks less to the past. "The problem with Muslims is that they know too much history," half-jokes Joe, a charity fundraiser who carries some semblance of his father's face in his broad nose and brow. "We're always looking backwards and blaming everything."

During the rest of my visits, Siraj introduces me to a wide array of others. Among them is Shafiur 'Shafi' Rahman. Shafi is another part of the identity/Islam chain. A business graduate whose father was one of Britain’s first Bangladeshi travel agents, Shafi manages Nafas, a community-sensitive drug project. Counselling, medication – and occasionally faith, if requested – are used to tackle Banglatown's burgeoning drugs problem.

"It's quite in your face in the area, on the estates," explains the 34-year-old. "We have a huge number of youth, too, so it probably seems more pronounced than elsewhere." A committed member of the East London Mosque, he talks of overcrowding, underachievement and unemployment all contributing to heroin and crack cocaine use amongst men and women alike. Kids are often used as runners by dealers higher up the chain, the gangs here merely the footsoldiers in a wider war. Interestingly enough, Shafi reveals that Monica Ali visited Nafas for an hour whilst researching her book.

After meeting Shafi I take the chance to drive around the estates with Siraj, and to talk with Khalid, his softly-spoken colleague – and ex-gang leader – from the Tower Hamlets Rapid Response Team. The two are called out to deal with the huge gang problem unfurling across the borough, across its different races, this week's clashes marked in colour on a map pinned to their office wall. When I last spoke with Khalid only a few days ago, he had to drop the phone to rush out and deal with a shooting. It makes you realise what different worlds the people here inhabit. Perhaps we all do.

For it was just two years ago that I drove these same streets with Dave Hill, ex-leader of the East London branch of the far-right British National Party (BNP). A heavy-set, powerful figure with a streak of grey hair now lacing his dark pony tail, 35-year-old Dave is well-known inside the far right. Our first meeting in the drab surrounds of a Stepney pub – not a mile away from where Siraj lives, and not far from where Oswald Moseley and his blackshirts would gather – took place among half-draped St George's flags and the greying atmosphere of decay. Of something passing away. But Dave was proud of his British heritage: "My family's been 'ere for 250 years."

Expelled from the BNP, he lives alone with his mother and has links to Northern Irish Loyalism, telling me he has been in Belfast some 15 times. When I ask what the main problem in the area has been, his response is swift. "The Asians. Without a doubt." But this seems a losing battle. The BNP may have had a councillor, Derek Beackon, elected to the Isle of Dogs in 1993 but it was short-lived. People like Dave are a shrinking minority.

Our last encounter was but a week ago and despite appearances, I had to think hard about meeting him. Siraj had described the vicious racism he suffered for years at his school: where a friend was stabbed in the lift and even the caretaker told him he was a "Paki bastard" who should get back to his own country. Siraj got his revenge. “I’ll show you," he said. He became the school's youngest ever governor four years later.

But the Poplar streets not so far from Dave's home are hostile territory. For 'Ish', however, a charming but slightly eccentric young man of Pakistani origin – who tells me he's both a Sufi Muslim and a "social manipulator" – the neo-nazis are found not among the old Cockneys but in the latest arrivals: "The Eastern Block".

Making it sound like a turf war is already brewing, Ish claims East European immigrants and asylum seekers – "Serbians claiming Polish citizenship" – are involved in conflicts with the Bengali gangs, and frequently abuse the locals. "Only they've got guns," he says. "It's a very fascist attitude from the newcomers, like 'you're less than us'."

"I'm involved in the resistance," he adds enigmatically, fending off an Arab approaching us to buy 'weed'. "Because the Asian community here doesn't have much faith in the police. That's the main problem that's rising now. Other than that," he says without a hint of irony, his voice clear, "it's one of the most comfortable areas in Europe."

Away from Ish and his charm for young white women, out of the bar on Brick Lane in which I found him, even Siraj agrees with part of this prognosis. He tells me over the phone how he saw three Lithuanian guys, drunk, kicking and abusing Bengali elders outside a shop. "I was really surprised."

Jonathan Myers is not. For him, the area has been changing rapidly since he left in 1979 to live in Israel, ending up fighting a war in foreign lands against Islamic militants. With bags sitting under his brown eyes, Jonathan, 41, is a Sephardic Jew. His is a family history going back here hundreds of years – and now he's an outsider. He feels the recent changes are insulting to memory. "Could you imagine calling it Yidsville when it was populated by Jews?" Sorrow consumes him. "Jews have abandoned the East End. Forgotten their routes, changed their accents. I won't."

But change is omnipresent here. Who can tell what tomorrow will bring?

This article was commissioned for The Independent ©2004

If you enjoyed this article, you might want to read Bombs in Banglatown and Out of the Abyss or Gangbusters