The Islamic State, formerly known as the Islamic State of Iraq and al-Sham (the Levant), is a Salafist-Jihadist organization in control of large parts of Deir ez-Zor and ar-Raqqa, as well as eastern Aleppo and Homs, and parts of western Iraq. IS comes directly from the al-Qaeda affiliated Islamic State of Iraq (ISI), one of the leaders of Sunni insurgency following the U.S. invasion of Iraq. Initially, in 2011, ISI secretly sent Syrian member Abu Muhammed al-Julani into Syria to form the al-Qaeda franchise Jabhat al-Nusra. On 8 April, 2013, ISI Emir Abu Bakr al-Baghdadi publicized this and declared JAN and ISI to be merging under the name the Islamic State of Iraq and al-Sham (ISIS). Al-Julani rejected this and al-Qaeda leader Ayman al-Zawahiri ruled that the two linked groups should remain separate. War eventually broke out between ISIS and the rest of the Syrian opposition, including Jabhat al-Nusra. Following ISIS's conquest of the Iraqi city of Mosul, they declared themselves a worldwide caliphate on 29 June 2014, and changed their name to the Islamic State (IS).
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Rumored Affiliates within Syria
Yarmouk Martyrs' Brigade
an alleged Islamic State affiliate in Dara'a governorate
Harakat al-Muthanna al-Islamiyya
The Islamic Muthanna Movement is an independent Salafist group that was formed in 2012 and is active in Dara'a Governorate. The Islamic Muthanna Movement fields an estimated 2000 men. It has cooperated with Jabhat al-Nusra, Ahrar ash-Sham and other jihadist and salafist groups in various operations rooms. The Movement has cooperated with FSA groups in the past, but in late January 2016, twelve FSA Southern Front factions declared war on it.