Nazi Germany, of course. The first concentration camp was at Dachau, near Munich, in Bavaria. Founded in 1933. The first commandant, Theodor Eicke.
Hitler and other Nazis decided to start up the Holocaust.
The assumption in the question is false. The Holocaust is not 'start[ing] again'.
yes, in a sense. The modern state of Israel did not exist at the time of the Holocaust, Israel then only had one meaning: the Jewish people. Ie. all Jews were part of Israel.
You could argue that the Holocaust was the start of the modernity.
no
jews were the first who were killed at the stsrt of holocaust
The 20th.
WW2 started before the Holocaust.
At the time of the Holocaust, the nation of Israel did not yet exist.
The Holocaust was not a conflict. It was nass murder. Please see the related question.
yes Hitler did
A Holocaust is not a regular occurrence. It was a policy of genocide instigated by the Nazi German state up to 1945. Hopefully there will be no "next Holocaust".