Abu Bakr (Arabic أبو بكر )"Al-Siddiq" (ca 573 CE – 23 August 634/13 AH) was one of the earliest Muslims and a senior sahaba (companion) of Muhammad. Throughout his life, Abu Bakr remained a close friend and confidante of Muhammad. Upon Muhammad's death he became the first caliph (632–634), regarded by the Sunnis as the first of the Rashidun caliphs (first four righteously guided ). His caliphate lasted two years and three months, during which time he consolidated the Muslim state. Upon the death of Muhammad, some tribes rebelled, and in return he fought the Ridda wars against these Arab tribes to establish Islamic rule over all of Arabia. He also conquered the lands of Syria and Iraq.