Hey there!
At the Wannsee conference in 1942 the Nazis made plans to find a final solution to the "Jew problem". In their opinion, there were too many jews in their empire and they were looking for a way of getting rid of them (It sounds - and is - cruel, but unfortunately that's the truth). They found their 'solution' in the form of concentration and death camps.
The rules discussed were a follow-up of the Neurenberger laws (1935) which had as a purpose to isolate the Jews.
~ I hope this answer helps you!
