Rashidun: Information from Answers.com Mobile

Rashidun

First four caliphs of the Islamic community: Abu Bakr, 'Umar ibn al-Khattab, 'Uthman ibn 'Affan, and 'Ali. As Islam's first rulers after Muhammad, they assumed all his duties except prophecy: they led the congregation in prayer, delivered the Friday sermons, and commanded the army. The caliphate of the Rashidun expanded the Islamic state beyond Arabia into Iraq, Syria, Palestine, Egypt, Iran, and Armenia. They were also responsible for the adoption of the Islamic calendar and the establishment of an authoritative reading of the Qur'an.

For more information on Rashidun, visit Britannica.com.