Sunni Islam and Shia Islam are the two major denominations of Islam. Their division traces back to a Sunni-Shia schism following the death of the Islamic prophet Muhammad in the year 632. A dispute over succession to Muhammad as a caliph of the Islamic community spread across various parts of the world, which led to the Battle of Jamal and Battle of Siffin. The dispute intensified greatly after the Battle of Karbala, in which Hussein ibn Ali and his household were killed by the ruling Umayyad Caliph Yazid I, and the outcry for revenge divided the early Islamic community.In recent years, Sunni-Shia relations have been increasingly marked by conflict, particularly the Iran-Saudi Arabia proxy conflict. Sectarian violence persists to this day from Pakistan to Yemen and is a major element of friction throughout the Middle East. Tensions between communities have intensified during power struggles, such as the Bahraini uprising, the Iraq War, and most recently the Syrian Civil War and in the formation of the self-styled Islamic State of Iraq and Syria that has launched a genocide against Shias.