What on earth are you smoking?
Lots of things were "declared" in the Iraq War. But there never was an actual Islamic State in Iraq in any real sense. AQI/the future ISIS controlled no territory in Iraq after the Surge/Anbar Awakening and existed only as an underground terrorist cell. It would have remained such had it not been for the Syrian Civil War. ISIS as we know it today was born only when Syria became destabilized enough for Al-Baghdadi to move there in 2012 and establish, for the first time, an actual physical state with its capital at Raqqa.
Because actually, they DID own ground in 2006. Part of the reason for the surge was because there were areas that Coalition Forces (read USMC/USA/IA/IP) didn't go into. Which was the Thaylat, Sharikah, and Sophia Districts of Ar Ramadi. Al Anbar University in the Tamin District was also hotbed of activity and ripe recruiting ground.
On 17 Oct 2006, they held a parade down 17th Street in broad daylight passed the 17th Street Security Station (Marine Forward Operating Base). Which was in the center of Ramadi. Live footage made CNN/AL Jazeera et al, with the FOB in the background - I'd say that capability demonstrates "owning" the ground.
They also had Thar Thar, Saddamiyah, and several other areas where there was limited/no CF presence. They also held presence out west toward Ar Rutbah, and in the tribal areas going northwest toward Al Qaim with some some presence in Hadithah, Anah, Rawah.
In early 2007, The Iraqi Police in Ar Ramadi did clearing operations from the Joint Coordination Center (aka Snake Pit) to the Ar Ramadi Hospital in the east. Much of the ISIZ/JTJ folks took off and went out to areas more remote in Iraq.
By late 2007/early 2008 they were coming back and establishing more of a presence.......only US mil wasn't doing as many kinetic operations and much of the IA/IP operations were tipped off beforehand.
For a bit, it became a back and forth between the IA/IP and the ISIZ.
Two days before I left in May of 2007, there were two simultaneous SVBIEDs at a cluster of kabob/food stands in 5 Kilo that caused over 20 IP casualties - they were loading the bodies in pick up trucks and taking them to Bravo (Ramadi) Surgical on Camp Ramadi.
My girlfriend at the time was an Army medic that responded to the K-call; those attacks were something like the 12th in 2 weeks; albeit the level of activity wasn't as high as it had been late 2006/earlier in 2007.
During and after the surge, places like Thar Thar and the hinterlands to the west/east/south of Ar Ramadi were still areas where ISIZ fighters remained and controlled unmolested - they no kidding OWNED the ground - to say otherwise is a lie.
Then it just became a waiting game until the drawdown and eventual removal of US troops.
Chaos in Syria, where many ISIZ had also been hiding out and building connections further enabled them to seize military equipment, money, and also to conduct more recruiting.
The leadership, infrastructure, caches, and expertise all existed and was well established before 2011.