What does Wiesel suggest by calling Auschwitz "this kingdom of darkness" and "this kingdom of eternal night"?

By speaking of Auschwitz as "this kingdom of darkness" and "this kingdom of eternal night", Wiesel relates the concentration camp to the concept of darkness. Darkness, in literary terms, is related to suffering, loneliness, evil, and depression. These concepts apply to the feelings of the prisoners who were interned in that camp, as well as in the other Nazi concentration camps that were installed by the government of Adolf Hitler.

Auschwitz was a concentration camp complex set up during World War II by Nazi Germany around the Polish city of Oswiecim, in the annexed part of Poland. It was the largest of all German concentration camps.