The origins of the former rebel movement the Forces for the Defence of Democracy (FDD), which now control Burundi's parliament, lie in the violent months after the killing of Burundi's first elected Hutu president.
By Robert Walker
BBC News, Bujumbura
The FDD joined the peace process after 10 years in the bush
The 1993 assassination of Melchior Ndadaye by Tutsi soldiers sparked a cycle of killings and counter-killings committed against both Hutus and Tutsis.
Against this background many young Hutus streamed into the hills to join the ranks of a new rebel group, the FDD.
Its struggle against the mainly Tutsi army from bases over the border in the Democratic Republic of Congo and Tanzania was long and bitter.
Up to 300,000 people are estimated to have been killed during the civil war and all sides stand accused of appalling crimes against civilians.
The FDD finally joined the peace process and entered the transitional government in 2003.
At its head was Pierre Nkurunziza - a former physical education lecturer.
Pierre Nkurunziza (l) was a PE lecturer
Like many Burundians, Mr Nkurunziza's family has been scarred by the country's bloody history.
His father - also a politician - was killed during government-sponsored massacres of Hutus in 1972.
Mr Nkurunziza has now become Burundi's president.
The FDD says its first priority in government will be to bring reconciliation.
The assassination of Ndadaye set off a wave of violence
Despite its past as a Hutu rebel group, the movement claims to have rapidly recruited Tutsis since becoming a political party.
The FDD also says it wants to tackle poverty and bring security to the whole country, which means negotiating with the National Liberation Forces (FNL) - the last active Hutu rebel group - and up to now a bitter rival of the FDD.
But many Burundians, including those among the Tutsi minority, are waiting see how the FDD will govern in practice.
The big question is to what extent it will allow real political space to develop - something other former rebel groups in the region have been reluctant to do once in power.
In neighbouring Rwanda, the ruling Rwandan Patriotic Front (RPF), which came to power after the 1994 genocide, has restricted political opposition and clamped down hard on criticism from the press and civil society.
Burundi's increasingly vibrant, independent media and non-governmental organisations are likely to be watching carefully for any similar tendencies.