From 1975 to 1979, Cambodia experienced one of the most egregious genocides our world has ever seen: between 1.5 and 3 million educated people were rounded up and murdered with the goal of starting Cambodia over at what the Khmer Rouge called Year Zero. I highly suggest reading more about the Cambodian genocide here.
To make my experience even more personal, my tour guide was an elderly woman who was 14 during the Cambodian genocide. She recounted how she was marched away from Phnom Penh by the Khmer Rouge and was forced to work in the fields with the constant fear of being killed for no reason by children empowered by the Khmer Rouge. Her parents were among those killed during the genocide. Her story was harrowing.
Today, Cambodians are still recovering but have made amazing progress and are proud of their amazing country, as they should be.