But when millions flee much harsher treatment into a mostly uninhabited land that is taking someone else's homeland ?

The land that includes today Israel and the Palestinian Territories holds today about 10 million people had about 0.3 million at the start of the 19th century. You know when Arab numbers began to increase ? When Jews started showing up with money and suddenly there were jobs.

WTF where they supposed to do ? Do you know my grandfather's brother, when he studied engineering in Poland way before the holocaust, had to stand at class near the wall because Jews were not allowed to sit in class. That is to say persecution did not start and stop with the Nazis.