They were not. This was the time before Jews were imprisoned, it was the time of political opponents, trade unionists and socialists/communists.
To be taught to support the Nazis.
Concentration camps
They were sent to concentration camps ...
concentration camps
Concentration camps were where the 'undesirables' were sent (e.g., the jews, homosexuals, etc.), whereas the gestapo was the secret police
Jews
The first people imprisoned in concentration camps in 1933 after the Nazis won the election were their political opponents, namely the Communists. This was welcomed at home, as it stopped the civil unrest and the street-fighting. It was also heralded internationally, with the New York Times doing an extensive article on the concentration camps. As more laws were passed, restricting the rights and outlawing various practices, more groups were arrested and imprisoned. The imprisoning of Jews for being Jewish would not start for another six years.
Jews and other people were imprisoned because it was believed that they would infect the purity of the Aryan people and nation. In other words, they were feared to have eventually destroyed the Aryan race. While the above is true, the Nazi's needed a scapegoat, and played upon long standing hatred, fear and misunderstanding of Jews. Most political systems throughout the world, throughout history have tried to find or have a scapegoat. It benefits a government to proclaim it is protecting the general population by having laws against a minority. These laws are often turn to focus upon other minorities. Jews to Gypsies for example.
The Concentration Camps were designed by the Nazi party in Germany to contain "undesirables," most notably the Jews. Other victims included Hitler's political enemies, Gypsies, and homosexuals.
Concentration camps were a fact of Nazi rule in Germany during the 1930s. Mass extermination in the death camps was post the invasion of Russia in summer 1941. I am making a difference between concentration camps as a prison for what were termed undesirables and those places where the Holocaust became a matter of Genocide. This does not mean that the older, original camps were in any way decent or proper, they were not. The difference was that, for the most part, the mass of murders were committed in the death camps in southern Poland between 1942 & 1944.
Their was no Jewish Concentration Camp but in total between 15-16 Million Jews were sent to Nazi Concentration Camps.
Six million Jews and five million "undesirables" were killed in concentration camps or elsewhere. The undesirables were people Hitler deemed not welcome in the pure Aryan Europe he dreamed of ruling. They were mentally ill, feeble minded, dwarves, human with anomalies and deformities, communists, Hitler's enemies, and anyone else he chose to throw in the concentration camps and extermination camps.