1920 was at the beginning of the wave of post-1914 turmoil of the end of empires. Europe had been swept by war and revolution, and nobody would have known how that was going to turn out. Poland was still about 10% Jewish. China was still in the "warlord era" before the rise and fall of the KMT. India (and much of the rest of the world) was still British.
For a sense of the quasi-feudal pre-war Europe, I will always reccomend A Time Of Gifts, Patrick Fermor's walk across Germany and Eastern Europe in the 1930s.