Mostly it goes back to the 1940's. There was more history of Zionism beforehand, Jewish settlers gradually coming in to live in the holy land. But after WW2 was the large influx and big push for a Jewish ethnostate. Aaand the people living there already opposed it from the start. And since then it's been very apparent why, because Israel pushes beyond the borders they were already given from Palestinian land, and militarily occupy the Palestinian land they dont yet claim.