The major difference between Europe and the Pacific was the approach. In Europe, the Allies needed to make one major landing before engaging in traditional land battle.
The Pacific theatre forced the Allies to make landing after landing and then hold territory on their way to Japan.
The US one in the Pacific by taking key islands and using airplanes to control the region.
There are many examples of civilizations trading because they don't have the things their trading for. Like Egypt and Nubia with gold and ivory, Mesopotamia, and Indus Valley civilizations with spices and textiles, China made a road for trading silk with other civilizations because they didn't have it.
The development of caravels and naos by Spain and Portugal respectively allowed long distance transport, making possible commerce between European kingdoms and Far East without going across territories ruled by Muslim kingdoms in Near East.
