The Caliphs are the ones who brought Islam together as one. They would later come up with a system that would elect the first single caliph, Abu Bakr.
The Islam Empire grew very fast and soon it was a very large religion to follow. The growth was mainly because of battle because most of the time the people they have captured the city of would adopt the religion and soon become followers of Allah
The Muslims elected Ali, Muhammad's son in law as the one caliphate and he was a great person to elect for he did a lot for the nation of Islam
The Sunnis and the Shi ' ah were the two main groups of Muslims who fought over which way was right, the Sunnis believed that the new Caliph should be an elected official because Muhammad had no rightful heir but on the other hand the Shi ' ah believed that Muhammad's relatives that are not direct deserve to be head
The Battle of Tours took place in France and it was the biggest fight the Islamic Nation would face because their religion would disappear if they would have lost that battle and that is why they won because they were not going to allow that to happen
The Battle of Tours is the battle that marked the extent of the Muslim territory outside of Europe if the Nation of Islam was defeated in this battle they probably would have died off.
A lot of people say that form 476ce to 800ce is the "Dark Ages" but in fact it was more of a golden age because in many different places inventions that would change the world for the better would come to life such as the Muslims coming up with the idea to be able to read the stars better than anyone ever has