Europe has certainly gained a lot of experience with fences over the millennia, not to mention walls like this one, which was of course built to keep people in. So learn about a couple more: 1. The first ghetto started in Venice to cage in Jews while squeezing as much as possible out of them.
1516 - Establishment of ghetto (foundry) in Venice as a place of confinement for Jews, whose goal is to gain maximum economic advantage from the Jews' presence (including taxes), while ensuring minimal social contact with population. Generalization of term to include all enclosed quarters of Jews in Europe