As an Austrian it is not uncommon to have stood in front of a massgrave.
I am, as I think many of us are, past the initial shock of the realization what people are capable of doing to other people. But that does not mean that I am not thrown, standing on the killing fields.

A shortish tuk-tuk-ride south of Phnom Penh there is Choeung Ek, the mosst well known of the killing fields. A audiocommentary guides you through the former orchard that is now a memorial for a history that seems much to recent to be a reality.

In 1975 Pol Pot and the Communist party of Kampuchea took over Cambodia. Their followers were dubbed the Khmer Rouge. Khmer simply means "Cambodians". "Rouge" not so simply put the party under the banner of the communist ideology.
In Paris, where Pol Pot studied, he developed his own ideas of radical marxism.
Ideas that would eventually lead to the systematic genocide of millions of cambodians.

As you slowly wander around in the parklike area you have to remind yourself that you are on the killing fields. Actually ON them. You only realize that once the voice of the audioguide tells you to try and not step on pieces of bone and cloth you may find lying in your way. Frozen in place you scan the ground. The voice tells you to refrain from picking up either cloth or bones.
Near my left foot I notice a bone sticking out at an angle. I did not realize I held my breath until that moment. I cannot tell what kind of bone it is. But I can tell it is one by the marrow that is still slowly desintegrating in the hard shell-like outerpart that is bleached a crumbly white. Even though the graves have been emptied bits of bone and cloth still wash up out of the earth with the yearly floods of the rainy season. The shallow dents in the earth that used to be five meter deep ditches still empty themselves of their recent history.
In December 1978 vietnamese troups entered Cambodia with the intention of introducing a pro-vietnamese regime. They succeeded in January 1979 and the leaders of the Khmer Rouge fled into the jungle.
Ironically, by the UN, the Khmer Rouge was recognized as the official government(in-exile) of Cambodia. A price many a western government was willing to pay to not see the Vietnamese in power. The Khmer Rouge even received financial aid for their endeavours.
They held a seat in the UN until 1990s!

I am still trying to wrap my head around this.