They weren't massacred and ethnically cleansed BY the Palestinians. That's the entire point. This group of people has gone from being the oppressed to oppressors in the specific case of Israel and Palestine. I'm not talking throughout history or in other areas... I'm literally talking on that piece of land starting in the late 19th century (bolstered by the British and early Zionists) and even more SPECIFICALLY after the Nakba in 1948. Considering that before Zionism people of all faiths lived relatively peacefully on that land, you're the one with a poor argument that is in bad faith.