Answer:
After World War Two, European countries lacked the wealth and resources to supervise their overseas territories. This allowed many European colonies (the majority in African and Asian countries) to unite during Europe's time of weakness, fighting for their freedom. This was prevalent in parts of Africa and Asia and helped promote African and Asian Nationalism.
Step-by-step explanation:
This of course is a simplified answer with many local and global variables and impacts to consider.
I hope this helped!