The idea of pan-Germanism, demanding the unification of all Germans in one state, including the German diaspora east of the imperial border, grew out of Romantic nationalism. Some pan-Germanists believed that Germans were ethnically superior to other peoples — including Slavs, whom they viewed as inferior to the German "race" and culture. The Nazi concept of Lebensraum in turn demanded "living space" for German people, claiming overpopulation of Germany and alleged negative traits of heavy urbanisation in contrast to agricultural settlement.