This intriguing book explores the reasons why people migrate: pushes—involuntary migrations—and pulls—voluntary migrations. The different causes include: population density or lack of resources; colonization and empire building; independence from colonization, population transfer, and ethnic cleansing; the slave trade and human trafficking; war or natural disasters; religious, racial, or cultural prejudice and persecution; and to find work. Historical migrations examined include: the very first human migrations out of Africa and the gradual spread of humans around the world; the rise and fall of the Roman Empire; the slave trade; the relocation of Native Americans; migrations due to drought and famine in Africa; migrations linked to the wars in the former Yugoslavia, Afghanistan, and Iraq; the Irish potato famine; the migrations of Jews around the world; and the "Great Migration" of African Americans from the south to the north.