To send money to their families. Chinese large-scale migration to the U.S. began with the First Opium War, a war started by Great Britain against the Chinese Empire in 1839 that lasted until 1842, in wich Britain forced China to recognize them as equals and grant them many unprecendented trade rights. Large-scale chinese migration to america was carachterized by young men who had left their families back home, chinese society was marked by many social nets such as guilds and sometimes they would finance the immigration, some villages and even whole regions arranged for most of their young men to immigrate to America in order to send back money.