Those 'ghettos' in Germany were Havaara camps. They were staging posts from where the Jews were being shipped to Palestine as per the Havaara agreement Hitler signed in 1933 with the Zionist leaders in Europe (the Rothschilds). The first Havaara Camp was built at Dachau and over the next few years at least 60,000 Jews were moved to Palestine. (A lot considering at that time the long journey was made by trains and ships).
The whole thing started going wrong in the late 1930s because in British controlled Palestine, the Jewish immigrants had formed paramilitary terrorist groups to run the indegenous Palestinians off in preparation for a new Jewish state. They carried out a campaign of terrorist attrocities including mass shootings and bombings in Palestinian markets and other public places.
Those terrorist operations put the British in a difficult position. They had initially supported the Zionist movement when they issued the Balfour Declaration during WW1, but as the authority in Palestine they had been mandated by the League of Nations to lead the Palestinians to self Governence. They were now stuck in the middle between Jewish immigrant terrorists and outraged Arabs demanding the British do something. It all came to a head in 1939 when the British Government published the White Paper outlining their response to the escalating violence in Palestine which was to heavily restrict Jewish immigration.
Those new restrictions left Hitler stuck with hundeds of thousands of Jews in temporary accomodation at the Havaara camps in Europe with nowhere to send them.
This was all the real reason for the outbreak of WW2 that they have lied about ever since. Hitler knew the only way to resume the Zionist Havaara operation was to use military force to take control of the region around Palestine from the British. To prevent a retaliatory strike on the German Homeland he took out two of Britain's main allies in Europe first, France and Poland. That was why he quickly overran France on his western border and Poland on the eastern one in Blitzkreig attacks before he started the campaign in N.Africa the following year.
(You may have always wondered why there was never an explanation for why that N.African campaign was fought or what the objective was. That was because post war 'historians' were trying to distance both the war and Hitler from their links to the Rothchilds and their Zionist takeover of Palestine.)
As WW2 ensued, the over populated Havaara camps became the disease ridden ghettos we now call concentration camps. As German infrastructure and supply chains were destroyed by allied bombing, conditions in those camps only got worse and worse. Because Hitler lost the war, he got blamed for all of it when the truth is the Jew terrorists that became the post war Israeli leadership brought about the demise of their own people in those camps in Europe by their terrorist actions in Palestine which they continued unabated after WW2. Very evil people who learned nothing and cared not about the holocaust and war they caused, except when they exploited it for political leverage in the United Nations thereafter.