Caliph Abu Bakr was the first caliph of the Rashidun Caliphate, serving from 632 to 634 CE. He was a close companion of Prophet Muhammad and played a crucial role in the early spread of Islam. After the Prophet's death, Abu Bakr united the Arabian tribes and led military campaigns known as the Ridda Wars to consolidate Muslim rule. During his short reign, Abu Bakr established the foundations of the Islamic state and initiated the compilation of the Quran. His leadership was marked by efforts to maintain unity among Muslims and to expand the influence of Islam beyond the Arabian Peninsula.