>>17835625
Because a bunch of Jews moved to the Levant m, bought land from the Arabs and were successful in building a large enough community that the UN settlement plan for British withdrawal from the region decided to create two partitioned states in which one had a Jewish majority and the other a Muslim majority. Much like has been performed elsewhere in the world in India/Pakistan, Ireland/Northern Ireland, Cyprus/Northern Cyprus, or Sudan/South Sudan.
The funny part is Palestinians today would literally kill for the settlement they rejected back then.