Trading and Expanding

I think that this whole section is mainly about two things, trading, and expanding. At the same time that some of the civilizations were expanding, they were also trading along the way. Most civilizations had something different to offer another civilization except for a few that didn't have any goods to offer to the outside world. These groups were the ones that tended to expand because of there naval success. After they expanded, they would then use those resources to trade with the outside world. The civilizations that did have something to offer from there lands, tended to stay in there lands, and not travel around seeking great fortunes. They were already self sufficient, and did not need to rely on any country for there success.