The main reason why the Chinese immigrated to the U.S. was because of the gold rush. The Chinese didn't have a reason to start a war or move out of their homeland. They didn't have a reason to search for a better life. They did not leave their land because they were financially stable. Asian did not experience revolutions that brought economic crisis, political problems, and social changes like Europe.
However, in the mid 1800s, the Asian systems and government began going through social problems. Because this was the first major crisis that occurred in China, the government began to weaken under the repeated foreign invasions. There was revolts that occurred and problems caused by over population. The rulers could no longer control the people who wanted to leave the country.