The surprising political origins of the term Sunni
We often think of religious denominations as ancient, fixed identities. However, the very name 'Sunni' emerged from the intense political friction of early Islamic civil wars, evolving from a way to describe a 'right path' into a specific identity forged through centuries of intense competition.
While Sunni Islam is the world's largest religious denomination, with an estimated 1.7 to 1.8 billion adherents, its identity was not a sudden emergence. The term 'sunnah' itself predates Islam, originally meaning 'the right path that has always been followed.' Its political weight intensified following the assassination of the third caliph, Uthman, between 644 and 656. During the second Civil War (680–92), the term became a way to distinguish those who avoided the 'heretical' teachings of warring factions like the Shia and Kharijites.
The development of the 'Sunni' identity was a process of centuries-long competition. Contrary to the popular view that Sunnism and Shi'ism were distinct entities from the start, both sects are actually the end products of long-standing ideological struggles. They used each other to cement their own doctrines. For instance, the scholar ash-Sha‘bi (who died between 721 and 729) helped popularize the concept after turning away from the fanaticism he witnessed in Kufa.
Theology and law further solidified this identity through the 'Six Books' of hadith and the four legal schools: Hanafi, Hanbali, Maliki, and Shafi'i. Over time, the designation expanded to include 'ahl as-sunna wa l-jama'ah' (the people of the Sunnah and the community). By the 9th century, scholars like Abu al-Hasan al-Ashari added layers of 'straightness' and 'truth' to the definition, creating a complex, multi-layered tradition that balances the Quran, the Sunnah, and scholarly consensus (ijma).
Source: Sunni Islam