ISIS is not a monolithic organization, it is a movement with three main origins: Al-Qaeda, Saddam’s government apparatus and local Sunni tribes.
This article aims to provide an overview over the history of ISIS.
It does neither aim for completeness, nor to provide an exact timeline of specific events.
1. Formation and Aims of Al-Qaeda
Al-Qaeda started a reaction to the miserable living condition in the arabic countries.
Its founder Osama Bin Laden, born in Saudi-Arabia, saw the reason for the repression in the nature of the arabic governments –
ruling with man-made laws and ruling with the support of infidels .
In the end, Al-Qaeda aims to unify the islamic world under the Sharia by overthrowing the local governments after stripping them from american support.
After its formation it supported the fight of the Afghans against the communistic leadership with the help of Saudi Arabian money and American weapons.
While the arabic fighters had neglectable influence on the war, money and organization helped them to spread to other countries and conduct attacks
there. Al-Qaeda operates decentralized; each country has its own Al-Qaeda branch. The branches communicate as little as possible for concrete attack plans
but give each other logistic support.
Of note is that Al-Qaeda opposed the Saudi royal family after 1990, because they opted for the help of the US instead of the local mujahideen .
2. Aftermath of the Third Gulf War
In 2003, Iraq had a 350000 men strong army with in total 9 corps, a secret service with decades of experience in keeping the population under control
and officers with exprience from the First and Second Gulf War . After the war, the US goverment disbanded the army and all secret services and dismissed
all civil servants from the Baath party . Without the repression, Al-Qaeda and Muslim Brotherhood offsprings started the insurgency against the US.
The leaders of Baathist loyalists and local Sunni fanatics were interned in the same place: Camp Bucca.
Nearly all ISIS leaders can be traced back to Camp Bucca, the Baathist officers saw a chance to take vengeance, the fanatics saw a chance to get militaric expertise.
Starting 2003 Al-Qaeda in Iraq was led by Al-Zarqawi. Al-Zarqawis tactics resemble the propaganda videos of the IS, and he was the first to talk about establishing
a caliphat in the middle east in the immidiate future :
The mujahideen in Afghanistan fought against militaric targets, Al-Zarqawi beheaded civilists and bombed Shia villages to stir hatred between Shia and Sunni in Iraq.
The second in command of Al-Qaeda, Al-Zawahiri, deemed this repulsive. This was the first time that the local ideas of the IS were in conflict with the
pan-islamic idead of Al-Qaeda.
In 2006 Al-Zarqawi died and Al-Qaeda in Iraq renamed itself in Islamic State in Iraq and in 2010 Al-Baghdadi became the leader.
Al-Baghdadi is a preacher who radicalized during the invasion and received training (and joing Al-Qaeda) in Camp Bucca.
While Al-Baghdadi is the leader, the militaric operations were planned and organized by
Haji Bakr, an ex-officer of the Iraqi Air Force, Al-Turkmani and Al-Bilawi, two ex-officers of the Iraqi Republican Guard.
The militaric doctrine of the IS is based on the Baathist doctrine, but is extended with more flexible insurgency tactics, especially in the defense .
ISIS also has perioic internal prugins conducted by ex-secret service officers, e.g. after Al-Baghdadi became leader in 2010 the supporters of the old leadership
were executed .
While the US remained control over Iraq, it was never able to fully suppress the insurgents – in 2010 Islamic State in Iraq was mainly supported by Turkey .
3. Arab Spring
In the revolts of the arab spring, Al-Qaeda saw itself confirmed that without western support the local governments were not able to stay in power.
In northern Africa the Muslim Brotherhood was partially able to channel the revolts and the IS spread from Iraq to Syria to claim the power there.
In January 2012 Al-Nusra was founded as an offspring and both organization openly participated in the civil war.
4. Civil War
Al-Nusra cooporated with local tribes and was the main power in the east of Syria, while the FSA (at that time yet consisting mostly of SAA deserters)
fought in the west. In 2013, Al-Baghdadi broke with the Al-Qaeda strategy that the local branches are responsible for only one country and
must aim to overthrow that government. He declared Al-Nusra as a suborganization, i.e. put them under direct IS command and attempted to kill their leaders.
Early 2014 Al-Qaeda officially broke all ties  and Al-Nusra and IS openly fought. Several parts of Al-Nusra deserted to IS and with the support of local Sunni tribes
the IS was able to swipe from the Iraq-Syria border to Kobane-Azaz end of 2015, though it retreated from Azaz.