The Belgians, who once ruled both Rwanda and Burundi, came with a strange form of race science. After concluding that the tall and thin Tutsis were superior to the short and stocky Hutus, the colonialists produced ethnic identity cards and favored Tutsis for all positions of power.
Resentment among the Hutu majority gradually built up. In 1959 riots killed 20,000 Tutsis and sent many more fleeing to neighboring countries, such as Uganda and Tanzania.
When Belgium granted Rwanda independence in 1962, the Hutus took over. For decades a Hutu dictatorship further polarized the ethnic state, blaming Tutsis for every crisis.
The originators of the 1994 genocidea small group of Hutu politicians from northern Rwandaharnessed the well-oiled state apparatus to their murderous cause, extending its tentacles to the grassroots level.
Local officials exhorted Hutu farmers to kill their Tutsi neighbors. Some farmers were told they could appropriate the land of those they killed.
At roadblocks the ethnic identity cards originally introduced by the Belgians proved invaluable to Hutu gangs. The gangs needed to know who was a Tutsi, and thus who should be killed.
The scars of genocide are everywhere in Rwanda today. In a church at Ntarama, south of Kigali, the remains of 5,000 Tutsis who had taken refuge there, many of them children, have been left to rot between the church pews where they were killeda haunting memorial to their brutal slaughter.
But the new government has abolished the ethnic identity cards, and it has promoted an ambitious program of national unity. Many former militia fighters who fled to neighboring Congo after the genocide have returned to Rwanda and joined reintegration camps, where they have been taught new skills.
Critics, however, say the new government is using the past to justify a de facto one-party state, virtually eliminating all political opposition in the process.
"This is an extremely disciplined and effective political organization that has incorporated a tradition of 300 years of strong control in Rwanda and turned it to its benefit," said Alison des Forges, a Rwanda expert at the New York-based Human Rights Watch.
The biggest problem may be justice. Some 100,000 people are still locked up in Rwanda's prisons. Only 11,000 cases have so far been handled.
Few of those who have confessed to killings have expressed sincere remorse, instead blaming what happened on evil spirits or the former government.
In 2001 the government started organizing village courts known as gacaca (meaning "on the grass," which is where they are to be held), in which elected lay judges would hear witness testimony from villagers.
Not a single trial, however, has so far been held. Some observers warn that if gacaca is extended throughout the country, it could increase the number of accused by as many as 600,000 suspects, making the process unmanageable.
A lack of trials would not sit well with genocide survivors, who have already been told they will receive no financial reparation, as first promised. It will also hurt innocent Hutus.
"If there's no establishment of who is guilty, that means there's no establishment of who is innocent," des Forges said. "That leads to a globalization of guiltthat all Hutus are guiltyand the consequences of that for any kind of future reconciliation is, of course, very, very serious."
After the Holocaust, the international community pledged "never again" to allow genocide to take place. Yet it did happenin Cambodia, the former Yugoslavia, and Rwanda.
By killing ten Belgian United Nations soldiers early in the three months of slaughter, the Hutu militias sent a message to the outside world: Stay out of Rwanda.
The tactic worked. Western governments avoided using "genocide" to describe the slaughter. Under the UN Geneva convention, calling the event a genocide would have obliged them to intervene.
The United States, stung by failure in Somalia a year earlier, vetoed any military intervention and successfully lobbied for the withdrawal of UN forces.
In recent years leaders of national governments and international institutions have acknowledged their mistake. During a visit to Rwanda in 1998, President Clinton apologized for not acting. While commemorating the tenth anniversary of the genocide, UN Secretary General Kofi Annan said he personally could have done more to stop it.
Many survivors I met in Rwanda over the years were understandably bitter about the international failure to stop the genocide, but some said they understood why.
"People forget," said Esther Mujawayo, who lost her husband in the genocide and started a support group for 18,000 widows of the massacres. "We are even forgetting."
In 1999, on the fifth anniversary of the genocide, Mujawayo was watching the NATO bombing campaign unfold in Kosovo. "When I saw the television news, I watched it and I turned it off," Mujawayo said. "Then I realized how easy it is to tune out."
On a lush hilltop outside Kigali five years ago, I followed Anastase Ndagijimana through a rusted metal gate into a school compound that was mostly destroyed when militias raided it in 1994. As a young choir sang inside the school, Ndagijimana bowed his head in front of a mass grave that included 15 family members.
"I can understand why no one came to help," Ndagijimana told me. "We are very far away in Rwanda."
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