But in 2003, Kibaki revoked that agreement and went back to the old habit of filling government positions – including, crucially, the Electoral Commission of Kenya – with personal allies and members of his own ethnic group, the Kikuyus. Furious at what they considered a betrayal, and cut off from access to power, former allies such as populist opposition leader Raila Odinga – a member of the Luo ethnic group who claims that he won the Dec. 27 vote – broke from the government and started a campaign for "majimbo," Swahili for self-rule, and resistance to Kikuyu domination.
"The fact that this violence was going to happen wasn't a surprise," says Waiganjo Kamotho, an attorney and political observer in Nairobi. "For months out in the Rift Valley, we've been hearing people saying "nyorosha," which means, 'We're going to straighten you up, put you in your place.' "
In the election, voters cast ballots along ethnic lines. Kibaki's support came from Kikuyus. Mr. Odinga, a Luo, drew mainly from his Luo tribe, but a coalition of politicians from smaller ethnic groups added to his base.
For most Kenyans, this tribal fight is not just about the presidency, but land – the ultimate source of wealth in a mainly agricultural society. And the Rift Valley – Kenya's bread basket – is the main battlefield, as small "indigenous" armies with bows, arrows, and machetes march to expel the Kikuyu "newcomers."