KHULAFAUR RASYIDIN ( Four Caliphs )

First four caliphs (Arabic: الخلفاء الراشدون) or Ar-Rashidun Caliph were four Caliphs (leaders) of Islam first, believed by Muslims as the successor to the leadership of the Prophet Muhammad after his death. Four of these were recorded Muhammad's closest and best known in the defense of the teachings he brought in the time of Muhammad's prophethood. The four caliphs were chosen not by his descendants, but by the consensus of the Muslims .
Electoral systems for each different caliphs, it was because of the friends assume no obvious references left by Prophet Muhammad about how the Islamic leadership succession will take place.