How was vietnam able to become and remain autonomous despite china's power and dynamism?

Throughout history, Vietnam was not totally free from China’s power and dynamism, having been under Chinese domination for different, interrupted time periods, the earliest being in 111 BC. Being a strategic southern territory, the Chinese used now-Vietnamese territory to launch expeditions to Southeast Asian states. The last Chinese occupation of Vietnam ended in 1427, with the Chinese Ming Dynasty accepting Vietnam as an independent, yet tributary state. 

the right answer is the end of world war ii

after the end of a global wwii all the nations involved, in an attempt to create an organization to maintain world peace. this agreement would work settling international disputes via negotiation and arbitration instead of leading the issues escalate to another war.