I grew up up in China. And I still have memories of Sino-Vietnamese War. I was in my early teens. It was a huge event at the time. Short-lived as it was (It officially lasted for one month in 1979, though the armed conflict lasted for the next ten years), the war was brutal. We heard news everyday from the radio. Back in China, we called that Defensive Counterattack against Vietnam.
Eventually the collective memory of the war went into the file of forgiving. I visited Vietnam three times in my adulthood. My impression of the country was peacefulness with beautiful land and water, even though one could feel past memories still weighed heavy there.