They were ethnically cleansed.
They were sold there, nearby.
It is a new term that came into use recently. But originally most fled out of fear even the armed ones left our of cowardice.
However, there were a few battles that were strategic important for them and tried to chase out. But the overwhelming part left, especially after the Mufti al-husseini told them so as well as other Arabs leaders to evacuate with promises that the Hews would be cleansed...and they will return gloriously.
BTW, most Arab Palestinians’ grandparents immigrated from other regions in the Middle East.