Last summer the Islamic State shocked the world with its lighting conquests of swathes of Iraq and Syria.
But the group is much older than that. It has its roots in Al-Qaeda and the global jihadist movement that developed from the 1980s onwards.
What is now the Islamic State began as a group called Jamaat al-Tahwid wa-i-Jihad (JTWJ), founded in 1999 by Abu Musab al-Zarqawi, who first became a jihadi in Afghanistan.
He met Osama Bin Laden in 1999 and the two always had a fractious relationship, which sowed the seeds for the later dispute between Al-Qaeda and the Islamic State.
Zarqawi was brash, abrasive and from a poor background. Bin Laden on the other hand was rich and did not feel the need to fight on the front lines.
Initially, JTWJ focused on trying to overthrow the monarchy in Jordan, but after the 2003 invasion of Iraq by the United States, Zarqawi joined the insurgency in Iraq against American forces.
He became famous for his ferocity and personal brutality as well as for his battlefield successes. Zarqawi’s personal hatred for Shiites remains an integral part of Islamic State ideology. He called them "a sect of treachery and betrayal … the lurking snake, the crafty and malicious scorpion"
Zarqawi led his jihadis in many high profile terrorist attacks. Some of the most brutal were an August 2003 attack on the UN compound in Baghdad that killed 22, including UN Special Representative Sergio Vieira de Mello, then considered the most likely successor to UN Secretary General Kofi Annan.
In February 2004 the group killed 150 people in simultaneous attacks in Baghdad and the Shiite holy city of Karbala during the holiest day of the Shiite year: the Ashura festival. Zarqawi was also known for his ferocity, in a particular his preference for carrying out beheadings personally.
In September he decapitated hostages Eugene Armstrong (American), Jack Hensley (American) and Kenneth Bigley (British) and broadcast the footage to the world.
In 2004 JTWJ formally became an Al-Qaeda affiliate when Zarqawi swore allegiance to Bin Laden.
The group then changed its official name to Al-Qaeda in the Land of the Two Rivers (the Tigris and the Euphrates). Most people called it Al-Qaeda in Iraq, or AQI.
Al-Qaeda in Iraq built up its own network of supporters and fighters during the Iraq insurgency. Although it was technically subordinate to Al-Qaeda central, in practice it did what it wanted.
It was in these early years in Iraq that Zaraqawi developed his ultraviolent brand of jihad that defines the Islamic State.
The founder of the group that became the Islamic State, Zarqawi’s example is followed by the Islamic State today. He is quoted on the first page of every issue of the Islamic State propaganda magazine Dabiq and honored by them with the title Sheikh.
“The spark has been lit here in Iraq, and its heat will continue to intensify – by Allah’s permission – until it burns the crusader armies in D?biq”
For more information see Clarion Project's Special Report: The Islamic State (ISIS, ISIL)