One of those realities is this: Not all wars produce terrorist groups, but terrorist groups often emerge from war. As Georgetown University’s Daniel Byman recently wrote, “Without the wars in the Middle East there would be no Islamic State.” Terrorist organizations “are rarely the cause of civil wars,” he noted; instead, belligerents adopt terror as a tactic or strategy, or terrorist groups move into a conflict zone and exploit the chaos.

This is what occurred in Iraq. Over the past year, ISIS has executed or inspired attacks in an increasing number of countries, in what may represent a shift in its targeting strategy. But the geography of terrorism is nevertheless highly concentrated, according to the Institute for Economics and Peace’s 2015 Global Terrorism Index. Seventy-eight percent of terrorism-related deaths in 2014, the latest year for which such data is available, took place in just five countries: Iraq, Nigeria, Afghanistan, Pakistan, and Syria. These are all battlegrounds. Iraq, Afghanistan, and Syria are experiencing civil conflicts, while the Afghan War has spilled over into Pakistan and Nigeria is menaced by the Boko Haram insurgency.

The institute reported that Iraq and Nigeria accounted for more than half of all terrorism deaths in 2014, and that the 9,929 terrorism-related fatalities in Iraq constituted the highest annual total ever recorded in a country—three times as many deaths from terrorism as had occurred in the entire world in 2000, the year prior to the 9/11 attacks. Iraq and Nigeria, the organization noted, are also home to the world’s two deadliest terrorist organizations: ISIS and Boko Haram, respectively.

Spikes in deaths from terrorism in Iraq coincided with the U.S.-led invasion of the country in 2003, the U.S. troop surge there in 2007, and the rise of ISIS—the reincarnated al-Qaeda in Iraq—in 2013. The last development contributed to a 55-percent increase in terrorism deaths in Iraq between 2013 and 2014.

Deaths From Terrorism, 2000 - 2014

Global Terrorism Database / Institute for Economics and Peace

In 2014, Iraq alone suffered a third of the world’s terrorism fatalities. Baghdad became the world’s deadliest city in terms of terrorism.

Countries With the Most Deaths From Terrorism, 2014

Global Terrorism Database / Institute for Economics and Peace

“The catalyst for the rise in terrorism in Iraq [was] the US-led invasion in 2003,” the institute argued. “From 1998 to 2002 there were 65 deaths from terrorism in Iraq. With the commencement of the Iraq war in 2004 there were nearly five times as many deaths than in the previous five years.”

In advanced economies, the organization concluded, factors such as a lack of economic opportunity, low levels of societal cohesion, and a country’s involvement in an overseas conflict seem to drive people toward terrorism. But in other countries, internal conflicts, political repression, and corruption appear to be the primary drivers.