The terrorist attacks in Paris remind us of the damage that a terrorist organization can do with even a little money. ISIS, however, is the richest terrorist organization in history. Last year alone, ISIS made over $1 billion. Much of that money was made from seizing state assets, selling oil on the black market and taxing people living in its so-called caliphate. Those sources of money are mostly internal and do not use the international financial system. But other sources of funding are more dependent on the outside world and may be easier to cut off. ISIS made nearly $50 million last year from kidnapping for ransom. ISIS is not the only terrorist group kidnapping hostages to make money. From 2008 to 2014, terrorist groups made roughly $165 million from ransom payments. Terrorist groups have long depended on criminal activity for funding including trafficking of cultural antiquities. ISIS is currently in control of hundreds of sites throughout Syria and Iraq. There are also wealthy donors, many of whom are based in Gulf countries like Qatar, Kuwait and Saudi Arabia, that voluntarily give money to terrorist groups like ISIS. Between 2013 and 2014, ISIS received as much as $40 million from these wealthy benefactors. These three sources of terrorist funding have given ISIS hundreds of millions of dollars in the last year.