Why did nazi Germany build concentration camps in Poland?

They chose Poland for the place for their concentration camps for 3 reasons (and possibly more):

- it was not on their territory, so they could hide from their own population the extent of extermination

- Poland had the biggest amount of Jewish Population at the time (around half of the Jews that were killed were Polish!)

-they hoped that if it was in Poland, they west would not notice as much as if it had happened for example in France.