After Syria's crisis begins, the group's leader Abu Bakr al-Baghdadi sends operatives there to set up a Syrian subsidiary. Baghdadi follows in 2013, breaking with al Qaeda and renaming his group 'The Islamic State in Iraq and the Levant'.
Islamic State faces the total defeat of its self-proclaimed caliphate. This timeline chronicles its lightning rise, cruel reign and stubborn fall.
In the chaos following the 2003 US-led invasion of Iraq, an al-Qaeda offshoot sets up there, changing its name in 2006 to Islamic State in Iraq.
So begins a reign of terror. In Syria, it massacres hundreds of members of the Sheitaat tribe. In Iraq, it slaughters thousands of Yazidis in Sinjar and forces more than 7,000 women and girls into sexual slavery. It beheads Western hostages in grotesquely choreographed films.
In September, the United States builds a coalition against IS and starts air strikes to stop its momentum, helping the Syrian Kurdish YPG militia turn it back from Kobani on the border with Turkey.
In May, IS takes Ramadi in Iraq and the ancient desert town of Palmyra in Syria, but by the end of the year, it is on the back foot in both countries.
Alarmed by the Kurdish advances near its own frontier, Turkey launches an offensive into Syria against both IS and the YPG. Enmity between Turkey and the YPG will continue to complicate operations against IS.
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