<span>Corps of Discovery Expedition</span>
made it hard on soliders and civilians to get money food.
Japan remained neutral, fearing reprisals from more advanced militaries. Japan was colonized by the United States and forced to modernize. Following the model of Western imperialism, Japan expanded its empire. Japan opposed imperialism and fought for Asian sovereignty.
Agricultural development led early societies to settle. Settlements required growing food and a lasting source of water. That's why these early civilizations were born around rivers. The proximity of rivers facilitated access to fertile soil and, logically, to water.
Once a civilization has a stable source of food it can start growing surplus of it, which creates the possibility of trade. That is, stable food production is a base for the complexification of a society that can lead to the creation of other jobs, like the merchant.
It also enables a society to complexify its social structures, to build cities, to develop religion and culture which creates more jobs.
