The whole point of the camps was to house undesirables, so better to ship these people off to the far corners of your land as to be out of the way.
___
The extermination camps were nearly all in Poland for the very simple reason that before the war Poland had by far the largest Jewish population.
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.
The most famous World War 2 concentration camps were located in Auschwitz (Poland), Dachau (Germany), and Treblinka (Poland). These camps were established by the Nazi regime and were responsible for the imprisonment and killing of millions of people during the Holocaust.
All Nazi concentration camps and death camps were run by the SS (except in 1933-34).
There were around 20,000 concentration camps and subcamps established by the Nazis throughout Eastern Europe during World War II. These camps were used for various purposes, including forced labor, mass executions, and extermination. Auschwitz-Birkenau, located in Poland, is one of the most notorious Nazi concentration camps.
From 1940 onwards most of the very large concentration camps were in Poland or in areas annexed from Poland. they varied all in germany. Europe held a lot of the concentration camps. they lived in germany.
Most, if not all, experiments happened in the concentration camps.
The most famous concentration camp was called Auschwitz and it was a network of Nazi concentration and extermination camps built and operated by the Third Reich in Polish areas annexed by Nazi Germany during World War II.
According to numerouse sources and figures, Their's an estimate of 34,000 Jews were sent to Auschwitz from other Nazi Concentration Camps or Sub-Camps. According to most Historians, it widely agreed that 33,734 Jews were sent to Auschwitz from other Nazi Concentration Camps or Sub-Camps.
As soon a the Germany surrend to the united states . they search over Germany to kill all Germans soldiers and once the alert was given that Hitler commited suicide they as well surrended and let all those Jews who were able to stand and walk free .
With the take over of Germany by the Nazi's in 1933, Leon Trotsky called that situation "The unparalleled defeat of the German proletariat the most important event since the Bolshevik revolution." The Communist Party was destroyed in Germany by the Nazi's and its leaders killed or sent to concentration camps.
All the main extermination camps were in Nazi-occupied Poland. There were also two in Belarus. Please see the related question.
Well technically the first groups affected by the Concentration Camps were Criminals and Political Opponents of the Nazi Party. However, the earliest and most effective group to be effected by the Concentration Camps were the Jews.