Finances of the Islamic State – Khorasan Province
The Islamic State's Khorasan Province (ISIS-K) has historically relied on three primary sources of funding: payments from ISIS-Core, local taxation, and international donations. In a 2015 interview, an officer of Iran's Islamic Revolutionary Guards Corps (IRGC) commented that ISIS-K's real source of power in the region was in the organization's financial wealth.
Source: Wikipedia — Finances of the Islamic State – Khorasan Province (CC BY-SA 4.0)