1 they were called concentration camps so the prisoners in the camp could concentrate on there bad decisions such as being Jewish and other reasons
3 the first concentration camps were pretty dirty places and prisoners lived on Baraks and we're usually starved and many of them died from either getting gassed or burned
4 they started killing more and more people
6 some may have experienced a lot of there friends and relatives getting killed and some may have experienced getting saved by soldiers invading Germany
While it could be from literally anywhere, I'd assume most of them came from the Soviet Union, Germany, France, and Poland, along with plenty of other smaller countries like Austria, Hungary, and even Greece.
