Jews were persecuted throughout Europe for centuries before the Nazis turned their sights on them. During the Roman Empire, Jews were fed to lions at the Colosseum for entertainment. Later, Jews were blamed for blood libels and spreading the plague. In the fifteenth century, Jews were given the choice of converting to Christianity or facing death. Pogroms and massacres took place in eastern Europe in the ninteenth century, killing hundreds of thousands of Jews.

Still reeling from the Treaty of Versailles which required Germany to pay reparations and concede land, the Nazis were eager to find a scapegoat for Germany's post-war decline.

The Nazis did not invent anti-semitism.  They just used it to gain and maintain power. Anti-semitism is thousands of years old, and most likely stems from the refusal of Jewish people to change their way of life and religion and because once they were dispersed from their own country, Israel, they were "foreigners," no matter  what countries they lived in. Spain, in the 14th century, killed Jewish people who refused to convert to Catholicism.  England, during certain periods of its history, did not permit Jews to live there. Other European countries had policies whereby Jewish people could not vote, own property, etc. Most "isms" stem from a people's "otherness," and since Jewish people were different, anti-semitism was a consequence early in their history.