The moment
When Muhammad died in Medina in 632, Muslims disagreed over who should lead. Most accepted Abū Bakr, chosen at a meeting of Medinan and Meccan Muslims, while some held that ʿAlī, the Prophet's cousin and son-in-law, was his rightful heir. Later Sunni and Shiʿi memory traces its divide to this moment, though distinct communities took shape only over the following centuries.
People: Abu Bakr, ʿAlī ibn Abī Ṭālib, Fāṭima