What is the primary historical basis for the division between Sunni and Shia branches of Islam?

Explanation

– The primary historical basis for the division between Sunni and Shia branches of Islam relates to differing views regarding rightful leadership succession following the death of the Prophet Muhammad (PBUH).
– This historical question regarding leadership eventually developed into broader theological and jurisprudential differences between these two branches over subsequent centuries.
– For exams, note that both branches share the same fundamental scripture, the Quran, and both affirm the core Five Pillars of Islam and Six Articles of Faith.