President Mwai Kibaki's disputed re-election at the end of 2007 triggered mass rioting and ethnic slaughter across the country.

Kenya's December 2007 presidential election was its most closely fought vote since independence from Britain in 1963. Rioting erupted when Kibaki, the incumbent leader, was declared winner of the poll, defeating opposition candidate Raila Odinga, by a narrow margin.

The violence quickly took on an ethnic dimension with fighting between members of Kibaki's Kikuyu tribe - Kenya's largest - and an alliance of supporters of Odinga, who belongs to the Luo group, the Kikuyus' longstanding rivals.

Security forces cracked down hard on protests called by the opposition in defiance of a ban on rallies as both sides accused each other of vote-rigging.

More than 1,000 people were killed in weeks of clashes and at least 300,000 people fled their homes, according to the United Nations' emergencies chief John Holmes. About half of the displaced are still living in temporary shelters.

The violence hurt Kenya's key tea, tourism and transport sectors, and damaged the country's reputation as a haven of stability in a turbulent region and a peacemaker in Africa.

Mobs hacked people to death and burned homes, businesses and crops. There were also reprisal killings.

In one of the worst incidents, some 30 Kikuyu villagers were burned alive in a church near Eldoret in the Rift Valley in western Kenya. The attack was blamed on a mob from the Kalenjin ethnic group.

Youths also set up roadblocks across the Rift Valley, squeezing transport to surrounding countries which depend on Kenya's Mombasa port.

Some of those uprooted by the violence fled into Uganda. The irony was not lost on Kenyans, used to taking in refugees from conflict zones in Sudan, Ethiopia, Somalia and Uganda.

Violence also exploded in Nairobi's sprawling slums like Kibera and Mathare where mobs beat people to death and torched homes and kiosks.

A criminal Kikuyu gang called the Mungiki was blamed for some of the revenge killings.

Police killed scores of protesters.

Kibaki and Odinga accused each other of genocide. But Holmes said the term genocide - the deliberate attempt to eliminate a religious or ethnic group or nationality - did not apply.

The explosion of ethnic violence took aid workers by surprise. The head of the Red Cross in Kenya said his organisation had put in place contingency plans for the election but that "no one imagined the worst-case scenario".

The turmoil also affected the supply of food aid to the rest of the region, delaying deliveries to Sudan, Uganda and Democratic Republic of Congo.

Kibaki and Odinga eventually signed a power-sharing deal at the end of February 2008 after weeks of heated negotiations mediated by former U.N. chief Kofi Annan, and a new prime minister's position was created for Odinga.

However, 18 months after the violence there is still deep resentment among Kenyans that the perpetrators of the violence have not faced trial. The International Criminal Court (ICC) has vowed to prosecute the perpetrators if the coalition government fails to create a special tribunal to try them.

Annan has sent the ICC chief prosecutor Luis Moreno-Ocampo a list of 10 names of suspected chief perpetrators of the violence, heightening pressure on Kenya to establish a court. Nairobi political and business sources say that the 10 names include at least two sitting ministers: one from Kibaki's side, the other from Odinga's.

As the crisis deepened in January 2008 the United Nations appealed for $42 million in humanitarian aid.

The worst displacement happened in the Rift Valley where the United Nations said in early January 2008 that 100,000 people could face starvation.

Many of those who have been uprooted are still too frightened to return home. Others have nothing left to go back to.

People in the Rift Valley took shelter in churches or police stations. Thousands are still living in makeshift shelters in camps.

The government allocated $83 million in the 2008/09 budget to help resettle and provide compensation for the refugees, according to the U.N. Office for the Coordination of Humanitarian Affairs in Kenya.

However, activists and aid workers say many of the displaced have received little or no money 18 months after the violence.

Rape and sexual assaults soared during the crisis. A senior U.N. official said reported cases had doubled amid a climate of impunity for the gangs committing rape.

Aid workers said many women and children took to sleeping at police stations out of fear that their neighbourhood might be targeted during the night.

See this map from ReliefWeb to find out where people are displaced.

Kenya's 36 million people are split into more than 40 different ethnic groups. The main ones are Kikuyu (22 percent); Luhya (14 percent); Luo (13 percent); Kalenjin (12 percent); Kamba (11 percent), according to government statistics. The Maasai, Kenya's best-known tribe, make up a little over 1 percent of the population.

The Kikuyu come mainly from the agriculturally rich central highlands and wield strong economic power.

The Rift Valley is home primarily to the Kalenjin tribe of former president Daniel Arap Moi. But many Kikuyus have moved there and intermarried.

Moi ruled for 24 years until 2002 when he stepped down at a presidential election which was won by Kibaki, a Kikuyu.

Odinga, a Luo, comes from western Kenya near Lake Victoria on the border with Uganda. Odinga's Nairobi constituency, Langata, includes one of Africa's largest slums where a large Luo population is behind him.

Odinga's father, Jaramogi Oginga Odinga, was Kenya's first vice president after independence in a government headed by Jomo Kenyatta, a Kikuyu.

Odinga campaigned for Kibaki in the lead-up to the 2002 election, bringing with him Luo support. But the allies later fell out and Odinga became a leading opposition figure. When he lost the 2007 election, most Luos believed their ethnic group had been cheated of power by the Kikuyus.

Despite Kenya's reputation as an oasis of calm in a troubled region, ethnic flareups are common - especially around elections.

The worst incidents came in 1992 when some 1,500 were killed in land clashes in the Rift Valley region.

Tensions over land go back to the colonial and post-colonial period. Since independence from Britain in 1963, Kenyan politicians have claimed land for political patronage, dividing it among members of their tribe or giving it away to buy loyalty.

At independence, some of the country's best territory was taken over by the Kikuyu tribe - divided among those who had close ties with British settlers and others who backed the bloody Mau Mau uprising against the colonisers.

The land redistribution caused resentment because, in some cases, the territory appropriated by the Kikuyu had belonged to other ethnic groups before colonisation.

With the transition to multiparty politics in the early 1990s, politicians began to exploit the land issue to galvanise support. The political dimension to what appear to be largely ethnic clashes over land explains the spike in violence in the election years of 1992, 1997 and 2002.

Regional conflicts have made guns easy to acquire in Kenya and they are a common household item in some areas.

One of the bloodiest conflicts over land is in the Mount Elgon region bordering Uganda to the west.

Several hundred have died and tens of thousands have fled their homes in the violence, which has closed schools and health services, destroyed property, and disrupted farming and trade.

The war between rival clans of the Sabaot ethnic group erupted after a controversial government land allocation in 2006.

Critics of the allocation say it favoured the Ndorobo clan and government supporters, sidelining the more numerous Soy, many of whom were evicted from areas they had farmed for 30 years.

A Soy militia called the Sabaot Land Defence Force (SLDF) has killed Ndorobos and anybody associated with the government.

The police have been accused of brutality and burning homes of people thought to sympathise with the militia. The police deny this.

The area which once exported produce to Uganda and other parts of Kenya is now dependent on several hundred tonnes of food aid each month, according to the Red Cross.

The Molo area in the Rift Valley is another volatile region. Most fighting pits the more numerous Kalenjin against several smaller tribes.

In 1992, Kalenjin politicians pointed out that land belonging to the Kikuyu had once been owned by Kalenjin. This resulted in the "Kalenjin Warriors" burning houses and taking land, causing many Kikuyu to flee. Several thousand have been killed and tens of thousands displaced in clashes since then.

Violence spiralled again ahead of the 2007 elections. Thousands of people are living in makeshift camps in Molo town after fleeing nearby Kuresoi where their homes and crops have been burned. Locals have blamed politicians for stirring up trouble in order to evict supporters of their rivals ahead of the vote.

Some of the other areas in Kenya where localised conflict has periodically broken out include Trans Mara, Meru, Bura, Central Baringo and Pokot on the Ugandan border, where cattle raiding is common between pastoralist groups.