The two world wars of the 20th century had a significant impact on the relationship between the European colonial powers and their subjects. The rise of communist Russia and the United States of America challenged the power of the old European empires like Britain and France.
The USA and Russia wanted to break the power of the old empires by promoting their ideologies of democracy and communism. These ideologies caused people to challenge the earlier assumptions that people in Africa and Asia were racially inferior. White Europeans' claims to superior intelligence and civilisation were no longer convincing, especially after the traumas and horrors they had inflicted in World War One and World War Two.