this decision goes back to the balfour declaration in 1917 (which king faisal had agreed with) and the palestinian mandate was secured by the leaggue of nations in 1922. it was peel commission in 1937 that recommended the two separate states because of the jews that were displaced their by having their german citizenship stripped, causing the subsequent arab revolt. it was to the jews, the promised land by the league of nations - their refuge from the nazis.
"We Arabs... look with the deepest sympathy on the Zionist movement. Our deputation here in Paris is fully acquainted with the proposals submitted yesterday by the Zionist Organisation to the Peace Conference, and we regard them as moderate and proper. We will do our best, in so far as we are concerned, to help them through; we will wish the Jews a most hearty welcome home... I look forward, and my people with me look forward, to a future in which we will help you and you will help us, so that the countries in which we are mutually interested may once again take their places in the community of the civilised peoples of the world."
king faisal 03 january 1919