ISIS was born from the merger of Zarqawi’s al Qaeda-affiliated group and al Dhouti’s Baath Party group that became al Qaeda in Iraq. During the Anbar Awakening the Baathist insurgent groups - even if Sunni- were getting aid from Iran and Syria. Al Dhouri had access under Assad’s regime to Saddam Hussein regime’s stash because al Dhouri was also the head of the Baath Party at the time.
Then when ISIS reinvaded they captured banks containing millions of dollars- the group has vastly more financial resources now than AQ did under bin Laden... and they won’t have to draw funds from any traceable western bank for a very long time, probably.
‘King of Clubs’ al-Douri?
While it’s been said he fled to Syria after Saddam’s overthrow & resides/resided in Syria, the Ba’athists (parties) in Syria & Iraq are 2 different animals, loathing each other; as was & is the case with ‘Safavid-shia-iranian-mullahs’ & a person such as al-douri who has been & still is a diehard Saddam supporter.
Don’t have time right now. A few more dimensions to this; maybe more later.
Though i agree ISIS is now pretty much financially ‘independent’ & does do trade with all sorts of people/groups. But if i were to venture an educated guess i’d say al-douri is infinitely more comfortable in ISIS controlled parts of Syria.