Which factors played a role in Chinese immigration in the late 1800s? Check all that apply.

According some authors which discuss this theme there were some factors as:

1) At the middle of 1850 the Chinese were still under British rule and the conditions were very difficult.

2) The devastation of southern Chinese by the taiping rebellion. This destroyed the rural economy and killed more than twenty millions people.

3) The gold was discovered in California in 1848. It produced a big immigrations at the final of century 17th.