I’m not an expert, but here is what I can offer.
In pre-colonial times, the notion of “Hutu” and “Tutsi” developed. While today, we think of them as ethnic catagories, it’s not a perfect description. Hutus and Tutsis speak the same languges, practice the same customs and religions, intermarry, and live in the same communities. In other words, they don’t, in a strict sense. display any of the differences that define ethnicities. But none the less, these notions deveoped.
When Rwanda was colonized, the colonial powers used the existing Tutsi royalty to implement indirect rule. This allowed the colonizers to rule the country and extract resources with relatively little manpower. The basic deal in indirect rule is that the colonizers provide support for their chosen ruling class, and the ruling class manages the day-to-day of keeping the population under control and extracting taxes. Anyway, using the Tutsi royalty as colonial instruments played a role in cementing “Hutu” and “Tutsi” as categories with political power behind them, and its in this time that ID cards started including ethnic information.
As independence loomed, a “Hutu liberation” movement formed, and some of the sentiment started to get pretty nasty. After indepedence, the Hutu majority gained power, and many Tutsis fled to nearby countries, where they maintained a fairly organized diaspora. Immediately after liberation, there was a great deal of violence as exiled Tutsis would stage attacks, and Hutus would retaliate.
In the decades after liberation, there were occassional, but signifigant, outbreaks of violence and reprisal killings, both within and outside of Rwanda. In the 1980s, there was a very well organized attempt by exiled Tutsis to gain power. This fed some very extreme ethnic rhetoric among Hutus, who characterized the Tutsi as power-mad foreign neo-colonial invaders bent on the re-conquest of Rwanda and enslavement of Hutus.
And this brings us to when the plans for the genocide were laid. A group of high-level politicians hatched the plan to “destroy the Tutsi”. Arms, primarily cheap machetes, were ordered in vast quantities. Radio personalities turned up the heat and gradually brought more and more hate speech into their acts. A command structure for the genocide was formed.
Then the president’s plane was shot down, nobody knows by who. This was, to the leaders, as good a time as any to start the genocide. Extremist leaders branched out into villages, recruiting, by enticement or by force, men to hunt down the “fugitive” Tutsis, who had fled to what they hoped were places of safety. Soon, the country became a free-for all, with the violence providing a reason to loot neighboring houses, settle old debts, and abandon the hard work of farming to feast on the much-prized livestock of the newly dead. Organized government-backed militia groups provided leadership and manned roadblocks, but most of the killing was done within communities, neighbor fighting neighbor.
The UN had stationed troops in the country to monitor a recent peace agreement. When it became clear there was a genocide in the works- and it was quite early on that this became clear- people on the ground tried their damnedest to get support. Looking back, it really wouldn’t have taken much to control the violence. Unfortunately, some Belgian troops were killed early on, and Belgium pulled out. The US, still smarting over their failures in Somalia, had little appetite for what seemed like a similar situation and lobbied the UN for a pull out. The UN hemmed and hawed about declaring it a genocide, which would require specific interventions, and until it was declared such, UN troops had no mandate to act except in self-defence. Nearly all Westerners were evacuated, often with militias waiting across the street to slaughter those they were protecting as soon as their vehicles pulled out. By the time the UN got it’s act together, the genocide was almost over, and all they could do was provide help at refugee camps, which in practice meant providing aid to the fleeing killers.
France, in particular, played a more active role in enabling the genocide. Rwanda had been (and still is) transitioning from a Francophone country to an English speaking one. France definitely supplied arms to the government, and may have provided more direct support.
As the genocide wound down, many Hutus fled to refugee camps in Zaire (now DRC). This caused all kinds of problems in DRC, none of which were helped by the fact that Rwanda has expansionist tendencies in the region and have been all up in DRCs business, causing the massive, continent-wide Second Congo War (which is the deadliest conflict in the world since WWII).
In any case, a new government was formed, discrimination was outlawed, and a somewhat effective authoritarianism has been the rule. Rwanda has grown well economically, and even become a bit of a darling in the West, and so the current regime gets away with a lot.
According to friends living in the area, the attitude now towards the genocide is mixed. Some people are eager to forget it, and don’t mention it. Others will bring it up casually, which can feel a bit surreal to a foreigner. For the most part, the great machinery of peace and reconciliation has done a reasonable job healing some of the wounds.