The Ottoman Empire had fallen after the British and French had won the war. They decided to split the Ottomen Empire into tiny groups and countries, which were very unfair as you'll see.
The British and French divided the countries not based on religion and ethnic groups, but based on their own profit. This would cause a lot of ethnic groups being divided, and enemies being together.
Anti-Semitism was a very strong thing after the 1st war. Many Europeans despised Jews, and discriminated them.
A lot of the Jewish people are some non-Jewish people felt that it was time that they got their original home back to them, Palestine. This belief was called Zionism.
All of the anti-Semitism caused Hitler to say that the Jews were the causes to all of Europe's problems, and the Holocaust happened. The Holocaust was the mass murdering, genocide, of the Jews. Over 6 million Jews died at death camps.