Camps for political prisoners were set up just after the Nazis came to power. I dont know whether you would call these concetration camps though...But yes if your definition of a concentration camp is a death camp such as Aushwitz/Birkenau then Ghettos came first. Either way the importnat thing to note is that the Nazis interned theit opponents and anyone they didn't like (e.g. Jews, gypsies. communists) and they did this through these camps adn ghettos.