Attacks by the self-declared Islamic State, itspredecessors and allies have left more than 33,000 people dead since 2002, researchers at the University of Maryland say in a report to be released today.

The report covers not just the core Islamic State group, which is involved in a bitter war with government forces and othersin Iraq and Syria, but also earlier groups that eventually morphed into the Islamic State and terrorist organizations that have pledged allegiance to it.

In all, some 30 organizations across Africa and Asia have thrown in their lot with the Islamic State, the University of Maryland researchers found, spreading violence from Nigeria to Bangladesh.

Erin Miller, the report's lead author, said her team conducted the study to figure out the breadth of attacks carried out by the Islamic State, which is also known by the acronyms ISIS and ISIL.

“It is sometimes difficult to answer questions the questions about what the patterns of ISIL terrorism are,” she said. “Our main goal was just to put current events into context.”

The researchers trace the organization's roots back to 2002 to a small network led by the Jordanian Abu Musab al-Zarqawi. The group became broadly known as the Islamic State in 2013,and has formed alliances to quickly extend its reach beyond Iraq and Syria.

In some cases, Miller said, the affiliations are loose and based largelyon ideological sympathies. But in others, such as the relationship between the Islamic State and Boko Haram, the ties appear to be tighter.

The researchers also tracked attacks in which perpetrators said they were inspired by the Islamic State — the main way in which the group has extended its reach into Europe, North America and Australia.

Such attacks have spurred debate about wealthycountries' vulnerability to terrorism. But the University of Maryland researchers found they account for a tiny sliver of Islamic State-linked attacks and are generally less deadly than those carried out by core members of the group.

In addition to the 33,000 people killed, some 41,000 people were woundedin ISIS-linked attacks, researchers found.

The team logged 30 terrorist organizations that had declared allegiance to the Islamic State's self-declared caliphate.

The United States is using a bombing campaign and special operations to try to dislodge the Islamic State from its strongholds in Iraq and Syria. In recognition of the group's growing impact elsewhere, the American military last week began bombing Islamic State targets in Libya.

Miller said the study helps show how widely the Islamic State's influence hasextended.

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