The Roma people arrived in Europe some time in the fourteenth or fifteenth centuries. They migrated from some place in the East, probably over several generations, with the most commonly suspected point of origin being somewhere on the Indian subcontinent. Like the Jewish people who were already well dispersed around Europe the Roma did not assimilate smoothly into the countries they emigrated to. They retained their social customs and religious beliefs and were distrusted by large sections of the local population. For much of the fifteenth and sixteenth centuries they were officially persecuted and banished by many of the societies of Europe and forced to migrate endlessly around Europe. State persecution of the Roma continues to this day in many countries.

The Boers were settlers who arrived in what is now called South Africa in the seventeenth century. They came, almost exclusively, from the Netherlands - although some were Huguenots from France and other European countries.

The territory that comprises the modern day state of Utah had long been settled by Native Americans when the first white settlers began to arrive in the nineteenth century. The first group to settle in Utah in large numbers was the Mormons, who were fleeing religious persecution in the East of the United States.

By 1998, the Croats had successfully found independence from their Serb occupiers. What's important here is that 1) Croats are a unique nationality, 2) Serbs are a unique nationality, and 3) the Muslims throughout the region are considered a nationality too. Following the Croatian victory, many ethnic Serbs living in Croatia did not want to be governed by the new Croats' government. So nearly thousands of ethnic Serbs fled Croatia for their “homeland” of Yugoslavia and Bosnia. Remember that Yugoslavia soon after devolved into Serbia-Montenegro, and the dictator Slobodan Milosevic was removed from power by his people.

For several decades of American history Ellis Island served as the point of arrival for immigrants coming to New York City and the United States from Europe and the rest of the world. Due to the vast numbers of Americans whose ancestors arrived via Ellis Island it retains a certain cultural significance even though the vast majority of contemporary immigrants arrive via plane or land borders.

The first inhabitants of North America crossed over a land bridge from Asia into North America approximately fifteen thousand years ago. Having arrived in the new continent it took little more than two thousand years before the descendants of these new arrivals had spread across the whole of the Americas.

Islamization, or the establishment of the Islamic faith, began pretty quickly as soon as it was introduced by its founder, Muhammad. It has grown through the ages across various countries, and even continents.

The “centroid” refers to the geographic center of the population of a country. So, if more people in a country live in the West than in the East, the “centroid” will be further west. The “centroid” of the United States has moved consistently west and south basically since the country was founded. This is because a larger and larger share of the population is living in the West and the South. This is primarily a consequence of migration from the East to the West and from the North to the South.

The “Sun Belt” is the name used to describe much of the South and West of the United States. Beginning in the second half of the twentieth century, cities in these regions experienced dramatic population growth as many Americans migrated away from the Northeast and the Midwest. Chicago is a northern city, so it is not considered part of the “Sun Belt.”

The “Great Migration” began in the late nineteenth century and continued throughout much of the early twentieth century. It involved the migration of African-Americans from the Deep South to cities like Chicago, Baltimore, Philadelphia, and New York - the industrial centers of the American northeast and midwest.