The unrest left nearly 200 people dead and 1,700 injured - with Han making up most of the victims - according to government figures.
Authorities in control
|Authorities have increased number of security forces in the run-up to the anniversary [AFP]
Al Jazeera's Melissa Chan, who was recently in Urumqi, said things there were quite different from last year, when the authorities were not in control amid the violence and chaos.
This time, troops appeared very much in control, in Han Chinese as well as Uighur neighbourhoods, and there was little tension in the air.
The authorities have gradually built up the number of security forces and staged massive anti-riot exercises in the run-up to Monday.
China blamed "separatists" and overseas Uighurs for orchestrating last year's unrest in the vast, arid but resource-rich region that borders Central Asia.
But Uighur activists deny the charge and say harsh policing, including the firing of live ammunition, provoked the violence. Thousands of people remain unaccounted for after mass raids by Chinese authorities following the violence, they add.
Rights group Amnesty International has urged Beijing to launch an independent inquiry into the violence, saying "the official account leaves too many questions unanswered".
Dilxat Raxit, a spokesman for the exiled World Uighur Congress, said they were planning protests around the world to mark the day, and repeated a call for Beijing to allow an independent probe of the riots.
"There is too big a gap between the numbers of dead China has announced and the reports we have received," he told the Reuters news agency.
Uighurs say the July 5, 2009 violence was sparked when police cracked down on peaceful demonstrations against government inaction in the face of a factory brawl the month before in southern China in which two Uighur migrant workers were reportedly killed.
More than eight million Uighurs - a Turkic-speaking people who have called Xinjiang home for centuries - live in the region and many complain about what they say has been decades of repressive rule by Beijing.
Many also complain about an influx of Han Chinese – China's main ethnic group – that they say leaves them economically and culturally marginalised in their homeland.
|Amnesty says the 'official account leaves too many questions unanswered' [AFP]
While standards of living have improved, as China's government often points out, Uighurs say most of the gains go to the Han Chinese.
Tensions in the city boiled over again in September after a spate of syringe attacks, which many victims blamed on Uighurs, led to days of protests that left several people dead.
The regional Communist party boss who was in charge when last year's violence broke out has since been replaced and state media report that the Urumqi security budget has been nearly doubled from last year.
But the deep-seated resentment that fuelled much of last year's violence has not been addressed, with Amnesty saying that a recently approved state development package for the region would not help, arguing that "without a credible independent investigation of the Urumqi riots and underlying grievances, resentment and mistrust will continue".
Uighurs say they struggle to find jobs and resent strict controls on how they practise their religion, Islam.
Han Chinese complain Uighurs are granted unfair perks because of their minority status, such as being allowed to escape strict family planning laws that limit most urban residents to one child.
"They have their scars, we have our scars. We mostly keep to ourselves. It's not good to discuss that period," a young Uighur student in Urumqi told the Reuters news agency, asking for anonymity for fear of reprisals.