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.
<span>Fernando Henrique Cardoso</span>
Sorry the answer took so long -laughs- but it only created a social hierarchy that stood for decades.
