So what were the causes for the Sunni and Shii orientations? The main polarisation between Sunni and Shii Muslims are not caused by any disagreements over doctrinal issues, rather it was as a result of some political events that took place in the early history of the Muslim society. Islam grew rapidly to cover vast geographic areas from India to Atlantic Ocean. This rapid growth inevitably posed tough challenges in administering the affairs of people. The main events that caused Shii and Sunni polarisation are listed below.

1. There was a perceived feeling of injustice when Ali, the cousin and son-in-law of the Prophet, was not elected immediately after the Prophet as the Caliph (steward, successor to the Prophet) of Muslims. Ali ended up being the fourth Caliph after Abu Bakr, Omar and Othman in the line of rightly guided caliphs. There was no apparent friction between any of these caliphs. Ali himself worked with his earlier predecessors as an adviser. It should be noted that the first four caliphs were elected or selected by various methods with the aim of identifying the most competent leader.
2. The disobedience of Muawiyah, the standing governor of Damascus, to Ali's orders to step down when Ali was elected the Caliph. Muawiyah said he would not step down until the murderers of Othman were caught and punished. This dispute resulted in an indecisive war between the caliph Ali and governor Muawiyah followed by arbitration between the parties.
3. Martyrdom of Ali when a renegade group attempted to kill both Muawiyah and Ali.
4. Sacrificial abandonment of the Caliphate role by Hasan, son of Ali and the grandson of the Prophet, in order to stop dissension and war.
5. Tragic martyrdom of Husayn, the second son of Ali and the grandson of the Prophet, at Karbala in 680 along with some members of his family and guards. This event was the main turning point.

Amid the explosive expansion of Islam and cultural, social and scientific advancements, the great majority of Muslims did not welcome such political events. All of these events somehow involved Ali and the family of the Prophet. All Muslims were gravely concerned about these events and abhorred the perpetrators of the injustices inflicted on some members of the family of the Prophet. However, a group of people, who deeply venerated Ali and the family of the Prophet, responded strongly to these events causing polarisation in the Muslim world. Taking the side of Ali, they were called Shii. They did not recognise the caliphate of Muawiyah who was now the undisputed Caliph of all Muslims. Shii Muslims believed that a non-pious Caliph who was not from the family of the Prophet should be removed by force. Sunni scholars and Muslims held the view that it was better to be patient and tolerate a non-pious Caliph for the greater good of keeping law and order in the Muslim land.

It is important to note that although these events and the resultant polarisation may seem negative and divisive, they are confined to the political sphere over a period of about 50 years. In ancient times, much greater political upheavals were expected in a large empire. These events were not bloody neither did they involve civil wars to include average Muslims. These events and the resultant rule of the Umayad Dynasty triggered many conscientious scholars into thinking about how a society could be run on a blend of Islamic norms. The discourse of religious experts gave birth to legal and religious disciplines of kalam (theology), fiqh (jurisprudence), hadith (traditions of the Prophet), history etc. Their works have preserved the sources of religion and systematise Islamic practice and law early on in Islam's history.