For those interested in where the Islamic State (IS) gets its money, the Congressional Research Service (CRS) has produced a report detailing the financial pathways behind this entity.
As the report notes:
While IS funding streams remain fluid, the group’s largest revenue sources appear (based on open-source information) to include oil sales, taxation and extortion, and the sale of looted antiquities. Oil sales initially provided the majority of the group’s revenue, but gradually declined as a percentage of overall IS profits due to an extensive campaign of airstrikes by the United States and coalition partners against oil and gas facilities used by the group.
The money flowing into IS is substantial, ranging into the millions of dollars per day. Consequently, senior U.S. officials view IS as one of the best-funded terrorist organizations – allowing it to administratively control and govern the territory it seizes.