Ancient cultural hearths are places where civilization first sprang up during the agricultural revolution that took place roughly eight to ten thousand years ago. All of these are notable places where the agricultural revolution took place except the Mississippi River Valley, which was not settled in large numbers until much later.

While diffusion is the more general movement of ideas, notions, and innovations, it can be broken down in its more specific functions. Contagious diffusion requires direct person-to-person contact, not the influence of trends observed in this question. Expansion diffusion deals with a single population, and so is insufficient for this multi-city movement. Diffusion by relocation is a sequential process in which the ideas are transmitted by their carrier agents (such as immigrants) as they evacuate old areas and relocate to new ones. While more appropriate than the first two, relocation is not quite as accurate an answer as hierarchical: a form of diffusion in which an idea spreads by trickling down from larger to smaller adoption units. Fashion is not being carried by people as they leave the larger cities, but is rather observed and adopted by smaller cities that don't have the means or resources to generate such ideas on their own.

Most people understand globalization to be a recent phenomenon - the permeation of American culture and consumerism around the world. However, globalization is a relatively old phenomenon as it only really describes the global homogenization of culture and experience through one dominant cultural tradition. What primarily separates the modern wave of globalization from previous iterations is the instantaneous telecommunication afforded by inventions like the internet. This connects people around the world instantly and has dramatically shortened the time taken to exchange media and ideas.

When an idea diffuses from its origin, but is changed or modified as it is adopted in other places, it is characterized as stimulus expansion diffusion, as opposed to being diffused in its original form (contagious expansion diffusion), diffusing from higher levels to lower levels (hierarchical expansion diffusion), or diffused by adherents moving into other regions (relocation diffusion).

Contagious diffusion involves a form of expansion in which people near the point of origin become adopters of a cultural fad. In the example above, the point of origin is the celebrity, and the townspeople become adopters of the Brand X fad. 

Diffusion is the spread of an idea or characteristic over time. When people move, or relocate, they spread ideas along with them. Therefore this is called relocation diffusion. "Distance decay" describes the process whereby interaction between locales decreases as distance increases.

“Acculturation” is the term used to describe the adoption of certain cultural and social characteristics of one society by another society. It usually occurs when one society is controlled, either politically, economically, socially, or all of these, by another society. And the people are forced to adapt their cultural experiences in order to survive in this new social climate.

Although Mexico sends far more immigrants to the United States than Cuba does in any given year, the majority of Mexican immigrants arrive in the southwest of the United States. Cuban immigrants tend to arrive, almost exclusively, in South Florida. This has contributed a great deal to the ethnic makeup of Miami, as well as its culture.

A “pidgin” language is a language that develops when two or more different languages meet in one geographic region- often when colonizers and the colonized live together in close proximity. The resulting language has elements of both the original languages. When a “pidgin” evolves into the primary language of a region it is called a “Creole” language.

The term “cultural appropriation” is used to describe a situation where a dominant social or cultural group takes an expression, idea, or product from an oppressed cultural group and uses it for its own benefit. So, the use of Native-American tribal names in American sports (Redskins, Blackhawks, Braves, and so on) is an example of cultural appropriation.