In 610 CE, the prophet Muhammad has a vision that ultimately led to the creation of Islam. However, when Muhammad died in 632 CE, people disagreed over who should succeed him as caliph. The Sunnis believed that Abu Bakr (his successor) was the right choice, which the Shiites disagreed, believing that the next caliph should've been Ali, Muhammad's brother in law. Still to this day, there is a definite split, and while they both have the same fundamental beliefs, neither get along well. This issue is especially prevalent in the Middle East where the majority of people are Sunnis, however the Shiites do not want them to hold power, so rebellion occurs. Likewise, when the Shiites gain power, the Sunnis rebel. The terrorist group ISIS is technically fighting for the Sunnis, however it is important to note that they practice a very radical form and do not represent the beliefs of most Muslims.
If, the war described in the question is referred to second war then:
This war was considered as the greatest war configuration in the history in the humanity unleashed by nazi Germany, fascist Italy and militaristic japan.
At the early years of the war the ally countries were France, england and soviet Union.
The largest losses corresponded to the Soviet Union wich lost 27 million people.
Explanation:
First Amendment: Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
However, determining the precise beginning and ending to any "period" is often arbitrary, since it has changed over time over the course of history.
Answer:
I believe it would most likely be because of a drought, flood, and/or temperature changes. Climate change also affects the food supply, meaning they were nomads and just trying to find food.
Hope this helps! God bless!