Complex sentence: Urban planning in Nazi Germany, the urban design and planning concepts used and promoted by Third Reich (1933--1945), was heavily influenced by modernist planning and involved totalitarian methods to enforce Nazi ideology on its native and conquered populations.
Split into simpler sentences: Urban planning in Nazi Germany refers to the urban design and planning concepts used and promoted by Third Reich from its rise in 1933 to its collapse in 1945. It was heavily influenced by Modernist planning and involved employing totalitarian methods to enforce Nazi ideology on its native and conquered populations.