Complex sentence: The book was printed by the Franz Eher Nachfolger publishing house and largely ignored at first, but sales began to boom in the late 1920s and early 1930s as economic depression and social unrest hampered Germany, factors which significantly boosted Hitler's popularity.
Split into simpler sentences: The book was printed by the Franz Eher Nachfolger publishing house and largely ignored at first. Sales, however, began to boom in the late 1920s and early 1930s as economic depression and social unrest hampered Germany, factors which significantly boosted Hitler's popularity.