You are probably thinking of the Auschwitz group of camps. Please see the related question.
Here are the name of the Major Concentrations in Poland during the Holocaust:AuschwitzBelzecChelmnoMajdanekSobiborWarsaw
Poland
Germany and Poland.
Most of the European Jews lived in Poland, Ukraine, Belarus and Hungary.
6. The death camps were the ones with gas chambers (or gas vans). The six death camps in Poland were:Auschwitz-BirkenauBelzecChelmnoMajdanekSobiborTreblinkaThe link below should have your answer.
Poland
The largest death camps were in Poland. Germany had death camps also but on a lessor scale. The Germans were responsible for all of them.
They were generally sent to Poland to the death camps.
Nazi Germany created the extermination camps on occupied Polish territory. (Germany had invaded Poland in September 1939).
I fear that horrible experiences occurred in all death camps. Most of the death camps of the Holocaust were in southern Poland.
Unfortunately, there were dozens upon dozens of death camps, or concentration camps as the Nazis preferred to call them. However, they were all centered in Germany and Poland. Poland was primarily where the camps were because that was basically 'Jew central'. It was also the first country in the war to be invaded and conquered.
The German occupiers set-up labour, concentration and death camps in occupied Poland. The Nazi created the death camps of Auschwitz II (Auschwitz-Birkenau), Chełmno, Bełżec, Majdanek, Sobibór and Treblinka. The Nazi German also created many concentration camps such as Auschwitz I.