Talk to many Angeleno African-Americans and Hispanics about the 1992 LA riots and they look back on it rosily. For people who were young at the time, it was the time of their lives.

"I loved everything that was going on," the rapper, actor and film-maker Ice Cube once told me enthusiastically; back then he was a 22-year-old who watched the smoke rise over the city from his home in Inglewood, near to South Central's LAX airport.

Another rapper, Mr Kane - formerly Kokane - lights up when as he reminisces: 'Oh shoot,' he laughs. 'I was doing a gang of looting. All of it got lost, but I got a gang of shit.'

Most people who were teens and in their 20s during the riot days have a story to tell about what they did - the things they saw, the places they went.

What sparked the LA riots is well known. But what kept them going in the face of armed police, reinforced by thousands of troops from the National Guard, the army and the police, is perhaps another, much stranger story.

To this day, the riots are recorded largely as a spontaneous mass act of disorder, sparked by two major news incidents.

The first is sometimes overshadowed by the second: in the spring of 1991 a 15-year-old girl called Latasha Harlins walked into a Korean-owned liquor store on South Figueroa Avenue, picked up a bottle of orange juice and put it into her back pack, before approaching the counter to pay. The storekeeper accused her of shoplifting and, after a tussle, shot Latasha in the back of her head. The whole incident was recorded on the store's in-house security video.

When the Korean woman who shot Latasha received a sentence of five years probation for involuntary manslaughter, African-American opinion in LA was outraged. Resentment of the Korean-owned stores was already high. For poor Korean immigrants, starting stores in run-down LA neighbourhoods was an attempt to gain a toehold on the economic ladder; but many African-Americans viewed the Koreans as outsiders who employed few black workers and sold up and moved on as soon as they could, taking money out of the neighbourhood.

That spring, another video camera filmed 28-year-old African-American Rodney King being beaten by police. The Latasha Harlins verdict was fresh in the minds of Angelenos when the four officers on trial for the prolonged roadside assault were found not guilty on April 29, 1992.
Around 3.30 that day, a young man in the wealthy Hyde Park district at West 67th Street and 11th Avenue threw a brick at a passing truck. Fighting broke out. A white pedestrian was chased, beaten and thrown into a skip.

Shortly afterwards serious rioting broke out at the junction of Normandie and Florence. People who looked white were being dragged out of their cars, beaten and robbed. From then on, pandemonium.

Over the next three days there were 55 deaths and 2,000 people were injured. Twelve thousand people were arrested and when the dust settled the bill for property damaged, burned and stolen came to over $1bn.

It's tempting to see the riot simply as political, a sustained protest against oppression, and in some ways it was.

In 1965 when furious African-Americans had burned down the Watts their rallying cry had been the inchoate fury of 'Burn baby burn!', a slogan purloined from a local radio DJ - the legendary Magnificent Montague - from KGFJ 1230AM.

This time, the rioters had a much clearer motivation. In the opening hours, rioters chanted the name of the unfortunate Rodney King. And in some ways the 1992 riot appears to have been curiously focussed - if a riot ever can be called that. In apparent revenge for the death of Latasha Harlins, 75% of the hundreds of corner liquor stores that were looted or burned were Korean-owned. But though the reason why rioters first lit fires may be clear, a different dynamic took hold once they were burning.

What shocked Angelenos was how fast and how far the riots spread. In all, fires burned in 163 square miles of the city. At the peak of the riots some well-heeled Beverly Hills residents believed the barbarians were hammering at their gates - that any minute the rioters would sweep northwards into the foothills of millionaire-land. And not entirely without reason. Hollywood residents were horrified when the northernmost rioters made it as far as Hollywood Boulevard. In the 1990s many Angelenos would have gladly torched the run down, prostitute-infested street themselves, but now the men of South Central were beating them to it and smashing the sex shop windows.

The very bastions of LA culture were at threat when rioters ransacked Frederik's, the world's most famous lingerie store. Items that were taken - never to resurface - included a purple and gold bustier donated to the shop's museum by Madonna. You kind of wish you were there now, don't you?

The real reason why many rioters were reluctant to stop their delirious rampage is maybe a more than simple politics. It was a rapper named Papoose who explained it best to me.

Before I pass to Papoose's explanation of why his personal riot kept on rolling, there is a slight irony that's worth pointing out.
I met Papoose because his hip hop group, Stranded, were about to release their debut album on a new label called Straight Alta-Pazz.
Straight Alta-Pazz was set up by none other than Rodney King, the sorry poster boy of the riots, the confused, beaten, some-time drug addict who had pleaded on TV for the mob to stop with the inadequate words: 'Can't we all just get along?'

By 1997 he had finally been awarded $3.8 million in compensation for his ordeal, but he didn't see much of it. A lot disappeared on legal fees. 'Once I got slaughtered by the police. Now I'm getting killed by the system,' King told me.

Much of the rest he foolishly ploughed into his own record label. One of the beneficiaries was former rioter Papoose.

Papoose grew up in the city of Compton, on the east of South Central's massive sprawl. Compton justifiably has a reputation as one of the most aggressive gang neighbourhoods in the city.

Quite how the poorest neighbourhoods of America's cities became so horrifyingly Balkanised is a long and complex story. At its simplest it goes back to the days of the massive population migrations of the first 50 years of the 20th century, when African-American farm workers from the South moved in tens of thousands to the industrial cities to find work in new factories.

They arrived in cities that were usually racially zoned. For much of the 20th century, complex housing laws forbade non-whites from moving into white neighbourhoods. Instead families crammed into ghettos like that around LA's Central Avenue. Newly arrived migrants clustered together.

Think of the hip hop term 'homeboy'. Its original use was simply geographic: my boy from back home. It embodies both the fraternity and implicit rivalry that was to become part of ghetto life, as economic migrant was set against economic migrant. Each new wave of immigrants - like the unfortunate Koreans - is pitched into the poorest neighbourhoods to sink or swim.

The 1960s briefly offered hope, but the Civil Rights movement gave little to ghetto dwellers, left behind as the new black middle-class emerged and left for classier districts.

In the 1970s, ghetto rivalry turned increasingly lethal as ancient neighbourhood rivalries became codified into territories controlled by street gangs. It was Los Angeles that gave us the Bloods and their eternal rivals, the Crips.

Papoose grew up in the city of Compton. Any hardcore hip hop fan would know the place: since the mid-1980s it's been immortalised in endless rhymes about its gang rivalries. Papoose's neighbourhood was run by the legendary Mob Pirus - a Blood gang.

Growing up in a gang neighbourhood has its hazards. The problems usually aren't so much in your own neighbourhood; it's when you leave it that the difficulties begin. You may not be affiliated to a street gang - few youths are, in fact - but that doesn't necessarily make any difference to a gang member from outside your turf.

Gang loyalties have grown complex over the years. They've become dynastic. I met one young man called Blue Diamond not far from Papoose's neighbourhood, who had the misfortune to be born to a well-known Crip father. When his father was imprisoned for murder, Blue Diamond was sent to live with his grandmother in Lynwood - a Piru neighbourhood. Blue Diamond never went out. He dared not show his face outside the door. He'd be a target. Instead he spent his teenage years sitting in a shared bedroom.

During the lawlessness of the LA riots it wasn't only formal laws that vanished. The so-called code of the streets also disappeared. For three days in April 1992, the gang animosities that kept young Angelenos locked into their neighbourhoods were suspended. There was talk later of a 'gang truce' but the reality was that the Rodney King trial suddenly provided a greater enemy than your immediate neighbour.

During those days Papoose, like thousands of others, roamed happily through the streets, unchecked by police or hostile neighbours.
'It felt good,' he explained happily. 'Because the tension was gone against the blacks. It had gone in another direction. I walked in neighbourhoods I have never walked through in my life, so it felt good to me.' It was like he was a tourist in his own city.

I have met dozens of people who said the same thing. During the riots they went to places they had never been before.

It was one of the reasons why people didn't want it to stop: when the fires went out, the old order would return. And sure enough, it did.
There is something awful about the way Papoose recalls those riot days, saying: 'It was the most love I ever got from other brothers, you know?'

We assume Britain's cities are a long way from South Central. In some ways they are. But you wonder whether right now we're repeating some of the mistakes America made in the 1940s and 1950s.

The Cantle report into the 2001 riots in Burnley, Bradford and Oldham concluded that people in Britain were leading 'parallel' and 'polarised' lives in which communities didn't mix. New immigrants found themselves pitched against older residents. Deprived communities are required to compete with each other for regeneration funding. 'Segregation, albeit self-segregation, is an unacceptable basis for a harmonious community and will lead to more serious problems if it is not tackled,' thundered Cantle.

Understandably, Karen Chouhan of the 1990 Trust bristles at the Cantle Report's mention of 'self-segregation'. Just as in America, the reasons why communities become set against each other remain largely structural, she says. 'The cohesion agenda is framed as though black and minority communities need to integrate more, whereas it's housing prices, education catchment areas and facilities that mean people cannot move. Polls show one in four white people don't want to live next to black people - not the other way round,' she says. 'If we're trying to force more integration on to black and minority communities what does that mean? Are we going to buy the houses for them? It's the ideology of blaming the victim and it's going to cause more problems down the line.'

In some areas of London and other cities, that disintegration may already be with us. When the 1990 Trust asked 800 children in Lambeth about their fears, one of their biggest concerns was the danger they experienced on their walk between school and home. 'They were spending a lot of time at school thinking about how they were going to get home safely,' says Karen. 'Life has already become fairly territorial for young people - even within boroughs on certain estates. A lot of young black people would not dream of going to certain very white areas.'

As in America, it's often the musicians who are the first to dramatise the ways in which young people's lives are changing. Dizzee Rascal was brought up in Tower Hamlets. In his short life he has seen the borough change dramatically as new populations move in, and tensions between residents are aggravated. 'The whole ghetto thing, whether it's forced or not, whether people want it, it's happening. I've been able to see it coming," he says. "It's mad, 'Cause they're starting to separate and segregate a bit. It's not a joke. They're all in their own zones.'

He says, 'Whether they want it to be like America or not, it's happening now in this generation of kids. And it's fucked.'