The Palestinian “Nakba” (“catastrophe” in Arabic) refers to the mass expulsion of Palestinian Arabs from British Mandate Palestine during Israel’s creation (1947-49).
The Nakba was not an unintended result of war. It was a deliberate and systematic act necessary for the creation of a Jewish majority state in historic Palestine, which was overwhelmingly Arab prior to 1948. Internally, Zionist Jewish leaders used the euphemism “ transfer” when discussing plans for what today would be called ethnic cleansing...

"In 1948 Zionist militias depopulated and destroyed more than 530 Palestinian towns and villages. An estimated 750,000 Palestinians were expelled from their homes, and many who were unable to flee were massacred. By the end of July 1948 hundreds of thousands of  Jewish immigrants from outside Palestine, many of whom were survivors of the Nazi Holocaust, had been housed in homes formerly belonging to Palestinian families like my grandmother’s. In December, the new Israeli state implemented a series of laws commonly referred to as the Absentees’ Property Law. These laws created a legal definition for non-Jews who, like my grandmother, had left or been forced to flee from Palestine. The laws allowed the newly created Israeli state to confiscate 2 million dunams (about 500,000 acres) of land from Palestinian families, including my own. In April 2015 the law was extended to cover land in the West Bank, thereby legalizing the continued expulsion of Palestinians and the confiscation of their land and property in order to house new Israeli citizens coming from abroad."