Yemen
The Yemen had been the first province to rebel against the authority of Islam when the tribe of Ans rose in arms under the leadership of its chief and self-proclaimed prophet Al-Aswad, the Black One, who was killed by Fairoz the Persian, while the Prophet Mohammad still lived, and thereafter Fairoz had acted as governor of Yemen at San'a.
When word arrived that the Prophet Mohammad had died, the people of the Yemen again revolted, this time under the leadership of a man named Qais bin Abd Yaghus. The avowed aim of the apostates was to drive the Muslims out of the Yemen, and they decided to achieve this objective by assassinating Fairoz and other important Muslim leaders, thus rendering the Muslim community leaderless. Fairoz somehow managed to escape and took shelter in the mountains. This happened in June or July 632. For the next six months Fairoz remained in his mountainous stronghold, where over the months he was joined by thousands of Muslims of Yeman.
When he felt strong enough, Fairoz led his men against Qais, and marched to San'a and defeated Qais, who retreated with his remaining men northeast to Abyan, where they all surrendered and were subsequently pardoned by the Caliph.
Read more about this topic: Ridda Wars