People cluster and cities grow because of what are broadly known as agglomeration economies. Agglomeration economies include things like knowledge spillovers that make workers and firms more productive, as well as the benefits that come from a thicker labor market, such as better employer-employee matches. Agglomeration economies are the forces that pull people together.
But when you move half-way around the world to start a new life in a strange foreign land, this process of trying to fit in is called acculturation. Researchers who studied the last great wave of immigrants to America, writing two or three generations ago in the mid-20th century, tended to give an either-or answer to this question. You could be either German or American. You could be either Chinese or American. We often assumed that becoming an American meant giving up on being German or Chinese.