What is the Holocaust? The Holocaust was the systematic annihilation of six million Jews by the Nazi regime during World War 2. In 1933 approximately nine million. Mar 1, 2013. The researchers have cataloged some 42,500 Nazi ghettos and camps throughout Europe, spanning German-controlled areas from France to Russia and. The maps the researchers have created to identify the camps and ghettos turn wide sections of wartime Europe into black…