I know. Anatman. I had disagreements between Buddhists in the Mahayana and Theravada schools in mind, though: I don't know of any escalating to violence(!), but the former calling the latter "Hinayana" (which is kind of like "The Inferior Way (to enlightenment)") is pretty petty. Nobody is immune to "my school of thought is better than yours" identity squabbling, unfortunately.

I think that some Buddhist practices are a pretty direct attempt to keep this sort of behavior in check, but still the old habits take a long time to simmer down. I think the central problem is when something in the animal brain mistakes criticism of identity for a physical threat. Meditation helps to see this for what it is and let it go, most of the time.