This timeline of antisemitism chronicles the facts of antisemitism, hostile actions or discrimination against Jews as a religious or ethnic group, in the 20th century. It includes events in the history of antisemitic thought, actions taken to combat or relieve the effects of antisemitism, and events that affected the prevalence of antisemitism in later years. The history of antisemitism can be traced from ancient times to the present day. For events specifically pertaining to the expulsion of Jews, see Jewish refugees.