Population density refers to the number of people living in a certain area of land. A country with a high population density has a large number of people living in a relatively small amount of land. Although the populations of the U.S.A., China, and Brazil are all higher than the population of Bangladesh, the land area of Bangladesh is much smaller, so it has the highest population density.

The eighteenth century was a time of dramatic population growth in Europe, particularly Western Europe. Advances in agriculture and fewer plagues meant a much lower death rate. The population rose from just under 100 million in 1700 to roughly 180 million by 1800. This population growth was vital for providing the conditions necessary for the Industrial Revolution to take off in the nineteenth century.

The term, "diaspora," is used to describe a group of people, or a nation, who have been evicted from their homeland and forced to live among other societies. In recent history this has been used to describe the community of Jewish people who lived in various European societies throughout much of history.  

The Amazon rainforest, and the Amazon River, are both found in Brazil, which is a country in South America. Central America is not a continent..

A monotheistic religion is defined by the belief in only one God. Judaism, Christianity, and Islam are all monotheistic religions. As is Zoroastrianism, an ancient Iranian monotheistic religion and philosophy. Of these choices only Hinduism is polytheistic, having a large range and variety of Gods.

Polytheism is a religion defined by the belief in more than one God. In the ancient world almost all religions were polytheistic—such as the Greek and Roman religions, Egyptian, Norse and so on; however, since the rise of Judaism, then Christianity and Islam, monotheistic religions (the belief in one God) now largely dominate.

Cultural diffusion is a term used to describe the spread of one culture’s language, ideas, or principles to other cultures, where it is then adopted and embraced. In the last century or two the English language has spread rapidly around the world and is now the second language of a large proportion of the global population.

The original Native American population is believed to have crossed into North America via a land bridge in the modern-day Bering Strait. So they would have crossed from what is now Northern Russia into Alaska and then rapidly worked there way (over many generations) down throughout modern North and South America.

A refugee is someone who has either been forced to leave or else has fled some disaster—famine, poverty, genocide, religious warfare, etc. A refugee leaves his or her own country and heads for a willing country believed to be safer. Different countries around the world have widely varied practices when it comes to accepting refugees. The diaspora is the name given to a community of displaced people, e.g. the Jewish Diaspora.

The phrase “God, glory, and gold” is often used to describe the motivations behind European conquest and settlement of the Americas. It is most frequently used to describe the first wave of European colonialism under the Spanish. It is a shorthand term to illustrate how the Spanish were motivated to colonize the Americas in order to spread Christianity ("God"), gain personal fame and notoriety ("glory"), and become immensely wealthy by exporting gold and silver back to Europe ("gold").