The Rashidun Army numbered more than 100,000 men at its peak. The Rashidun Caliphate is characterized by a twenty-five-year period of rapid military expansion followed by a five-year period of internal strife.

This term is not used in Shia Islam, as Shia Muslims do not consider the rule of the first three caliphs legitimate. These caliphs are collectively known in Sunni Islam as the Rashidun, or 'Rightly Guided' caliphs ( اَلْخُلَفَاءُ ٱلرَّاشِدُونَ, al-Khulafāʾ ar-Rāšidūn). It was ruled by the first four successive caliphs (successors) of Muhammad after his death in 632 CE ( AH 11). The Rashidun Caliphate ( Arabic: اَلْخِلَافَةُ ٱلرَّاشِدَةُ‎, romanized: al-Khilāfah ar-Rāšidah) was the first of the four major caliphates established after the death of the Islamic prophet Muhammad.