AT: "xx" A concentration camp or extermination camp was a location where people, usually civilians, were imprisoned. Those imprisoned usually belonged to a group regarded as undesirable or inferior by the authority imprisoning them. Invented in British Empire.
Nazi Germany operated many concentration camps during the 1930s and '40s, where millions of people were killed. USA and USSR also had such installations at the time.
In 2370, Quark told Benjamin Sisko that the Ferengi had nothing as barbaric as them. (DS9: "The Jem'Hadar")
In the original script, Quark mentioned the Auschwitz concentration camp.
In an alternate timeline, Vosk pitched the use of non-Aryan-targeting plagues as an alternative for extermination camps to a Nazi general. (ENT: "Storm Front")