the British , promised both them and jews this place in return for aiding them in ww1 (without the sides knowing about the other).
for 20 years since then, the arabs killed jewish civilians to scare them. after ww2 (in which the world was ashamed of ignoring the jewish holocaust) the jewish settlements demanded the british departure from israel (which the u.n granted them 3 years later)
There seems to be missing some rather poignant details from your history lesson, namely that the British left after only after Zionist terrorists assassinated the person charged with handling the transition, groups who were also responsible for numerous attacks on Palestinians. So, you see, it's not exactly like Arafat invented terrorism in the middle east, although he did employ it to great political effect. Without it the eyes of the world would simply have passed over the Palestinian problem, and therein lies the problem : contrary to what common sense should tell us, the middle eastern experience is that terrorism works.