The original difference between Sunnis and Shias is over who the true first successor to Muhammad is. Shias believe Ali ibn Abi Talib is the true successor to Muhammad, while Sunnis consider Abu Bakr to hold that position. The Khawarij broke away from both the Shias and Sunnis during the First Fitna (the first Islamic Civil War) and subsequently opposed both the Shias and the Sunnis, often violently.