Ever since the Hamas attack, I think I have understood the position of the Palestinians, that they were there first and then Britain unfairly divided up the landed and gave some of it to Jews so they could have a homeland where they wouldn't have to deal with Anti-semitism after what they went through during WWII.

But Jews/Zionists claim that they have some ancestral right to that land and I have not found it easy to come across anything from a reputable source that explains what backs up their claim (wikipedia and random YouTube videos don't count).