"The two great sects among Muslims, the Sunnites and the Shi'ites date back to the Umayyads. "The difference between these two sects is based on a political question, whether the succession to the Prophet should take place by election or by inheritance among the close relatives of the Prophet? This became a question of dogma to the Shi'ites, and the schism split into ramifications of its own and occasioned civil wars. It is one such uprising which swept away the Umayyad dynasty, and made it yield its place in 750 [A.D.] to the Abasids, but the Shi'ites did not profit by the change. In our days there are probably ten percent Shi'ites among the Muslims of the world, the rest being almost all Sunnites, not to speak of the infinitesimally small sect of the Kharijites, which also came into existence at the same time."
Shi'ahs acknowledge five collections of their own namely: (1) Al-Kafi (2) Manlayastahzirahu 'l-Faqih (3) Tahzib (4) Istibsar (5) Nahju 'l-Balaghah.