<span>When people in the united states hear that people in other parts of the world eat animals such as rats and bugs, they often react with shock, disgust, or horror as their culture shock makes them feel this behavior is wrong. Culture shock is defined as a sense of confusion and uncertainty that may affect people exposed to different culture or environment. Sometimes there are feelings of anxiety with culture shock.</span>
Since the question states that you need only one explained, the religion is the simplest because everything then was about Buddhism. It reached all levels of society and was widely practiced by many people, even described or seen thoroughly in works of literature or art.
Serfs were ranked somewhere near the bottom of the class system, just above slaves. They were peasants who were free, but were workers on territories owned by the feudal lords.