Original: In 1920, Adolf Hitler had just begun his political career as the leader of the tiny and as-yet-unknown German Workers Party (soon renamed the National Socialist German Workers Party, NSDAP) in Munich.
Simplified: In 1920, Adolf Hitler had started his political work as the leader of the very small and unknown German Workers Party (that was soon called the National Socialist German Workers Party, NSDAP (or Nazi Party)) in Munich.