2004-11: 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.
2011: After Syria's crisis begins, the group's leader Abu Bakr al-Baghdadi sends operatives there to set up a Syrian subsidiary. Baghdadi breaks rank with al Qaeda in 2013 and renamed his group "The Islamic State in Iraq and the Levant".
2014: Its sudden success starts with the seizure of Fallujah in Iraq and Raqqa in Syria. The jihadists take Mosul and Tikrit in June and overrun the border with Syria. At Mosul's great Mosque, Baghdadi renames the group Islamic State (IS) and declares a caliphate. So begins a reign of terror. In Iraq, IS slaughters thousands of Yazidis in Sinjar and forces more than 7,000 women and girls into sexual slavery. IS beheads Western hostages in grotesquely choreographed films.
♦ In September, US builds a coalition against IS and starts air strikes to stop its momentum, helping the Syrian Kurdish YPG militia turn the militants back from Kobani on Turkey’s border.
2015: Militants in Paris attack a satirical newspaper and a kosher supermarket, the bloody start to a wave of attacks that IS claims around the world. Militants in Libya behead Christians and pledge allegiance to IS, followed by groups in other countries.
♦ 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.
2016: Iraq takes back Fallujah in June. In August, the US-backed Syrian Democratic Forces (SDF), spearheaded by the Kurdish YPG, takes Manbij in Syria.
2017: IS suffers a year of catastrophic defeats. In June it loses Mosul to Iraqi forces after months of fighting and Baghdad declares the end of the caliphate in Iraq. In September the Syrian army races eastwards backed by Russia and Iran to relieve Deir al-Zor and re-extend state control at the Euphrates River. In October, the SDF drives IS from Raqqa.
2018: The Syrian government retakes IS enclaves in Yarmouk, south of Damascus, and on the frontier with the Israeli-occupied Golan Heights. The SDF advances further down the Euphrates and Iraqi forces take the rest of the border region. The United States vows to withdraw troops.
2019: IS fighters are defeated at their last enclave in Syria.