The history of the Jewish nation is a history of persecution. From the time of the Greeks and the Romans they suffered domination, oppression and even exile. In the years before the crusades they were completely driven from their homeland by the invading nations.
The persecution reached a new height during the holocaust. Since it was the first time their persecution was so widely and graphically documented through both print and visual media, worldwide awareness of the extreme cruelty and tragedy of the attempt to exterminate them as a people caused an outcry for justice.
With the formation of the United Nations after WWII and as the global community debated what to do about the situation, it was decided to give them back their homeland. In 1948 all of this was put into action.
This was good for the Jews, but not for the Palestinians, who by this time occupied the land. They were forced out, resulting in the conflict and warfare that continues to this day.