Cease fire that led to them splitting up
A) The shared experiences can dilute traditional cultures.
The red scare following World War 1 was caused primarily by fear of communist infiltration of the United States.
C. Siddhartha saw the teacher Buddha and liked what he taught, decided not to follow him. He went on his own path, fasted, found riches, gave it up, etc.
B. If you look at the dates, the earliest instance of the plague started in the south. Then, it continues to spread upwards and to the west, and the dates continue chronologically, from 1347 to 1349.