After 400 years of Ottoman rule, we the Brits took that region because we won WWI. We gave some to different Arab groups, and some to the Israelis. The muslim religious head of Jerusalem wrote fan mail to Hitler advocating for the Final Solution. The hostility toward Jews had been whipped up for years and the general unwillingness of the neighboring regions to agree to the lines that the UK delegated to the UN is why after we left the region descended into war. The Israelis held on to their land. The Iranian mullahs came along in the 70s and jumped onto the cause because they feed on hate. My father was an advocate of the Iranian regime, because he was a vulnerable conflict survivor with deep psychological issues. But I saw what they were peddling 45 years ago and I heard what they were inculcating in him, through the mullahs that they trained and sent to the UK. They love to stress the idea of Abraham sacrificing his children. These are people that use children in war. They fire their rockets and shoot their guns where their own civilians will get hurt in the counterattack because they are just pawns to them. They sent young boys to the frontlines against the Iraqis and they use human shield tactics against the Israelis. It's a tragedy when innocents die, but against a foe that uses innocents in the propaganda war, only steely resolve and self-preservation will rid this world of the scourge that is these Iranian mullahs.

Why the fuck does the colonial power dictate who “gets” land?

The land was stolen from the local farmers and fishermen and given to Europeans.