The opportunities avaiable to them and the amount of jobs they were able to get, they came for more opportunities and a better life
while on the revesre side they also faced discrimination based on races too
Bebeler gecelerde heceler
I understand from the question that it's not own lands that the country is taking over, but other, new lands, potentially already occupied by other lands.
This is then imperialism- the will to built an empire (such as the British Empire), that is, have more land under control.