FOCUS QUESTION How was massive migration an integral part of Western expansion?

A poignant human drama accompanied economic expansion: millions of people pulled up stakes and left their ancestral lands in the course of history’s greatest migration. To millions of ordinary people for whom the opening of China and the interest on the Egyptian debt had not the slightest significance, this great movement was the central experience in the saga of Western expansion. It was, in part, because of this global mass migration that the West’s impact on the world in the nineteenth century was so powerful and many-sided.

A note on vocabulary may be in order here: migration refers to general human movement; emigrants (or emigration) refers to people leaving one country for another; immigrants (or immigration) refers to people entering one country from another. When people migrate, they emigrate from and immigrate to.