Which nations prospered in the decades after ww2 and which fell into decline what types of policies led these nations to success or failure?

Western nations prospered in the decades after World War 2 while third world nations struggled to compete in the global market.

The league of nations was found in 1919 to keep peace after world war l.but it failed to prevent world war ll in 1939,so in 1945 the nations of the world set up a new organization,the united state (un).since then, the un has encouraged international cooperation and worked to resolve conflict