The Rashidun Caliphate ( ) is the collective term comprising the first four caliphs—the "Rightly Guided" or Rashidun caliphs ( )—in Islamic history and was founded after Muhammad's death in 632 (year 11 AH in the Islamic calendar). At its height, the Caliphate controlled a vast empire from the Arabian Peninsula and the Levant, to the Caucasus in the north, North Africa from Egypt to present-day Tunisia in the west, and the Iranian plateau to Central Asia in the east. It was the largest empire in history by land area up until that point.