The Global Terrorism Database (GTD) created and maintained by the University of Maryland is the most comprehensive database of terrorist activities with data available from 1970 onwards. The GTD defines a terrorist attack as:
The threatened or actual use of illegal force and violence by a non-state actor to attain a political, economic, religious, or social goal through fear, coercion, or intimidation.
Also, the GTD clarifies within its Cookbook:
The perpetrators of the incidents must be sub-national actors. The database does not include acts of state terrorism.
Below are some insights from the GTD data, taken as a decade by decade view with some spotlight explorations around the main terrorist organisations in each decade. The two immediate graphs below show a view of terrorist victims killed on a regional and then on a per country basis.


1970s
Terrorism in the the 1970s was primarily a challenge within Western Europe and in particular the United Kingdom with conflict centred around Northern Ireland. The graph below lists the organisations with the top 3 murder count over the course of the decade.

The Irish Republican Army (IRA) conducted an armed paramilitary campaign aimed at ending British rule and to create a united Ireland, with a counter response from Protestant groups including the Ulster Volunteer Force (UVF). The conflict stemmed from sectarian grievances between Protestants who were predominately settlers from mainland Britain seeking to remain part of the United Kingdom and Catholics who considered themselves marginalised and sought to restore a unified pre-colonial Ireland. A political settlement was finally reached in 1997 with the Good Friday Agreement, approximately three decades after ‘The Troubles’ started.
To note, a significant terrorist act took place in Iran during 1978 by the MEK of Iran, killing 434 people, although it’s motivation is cited as unspecified by the GTD.
1980s
The 1980s brought about a regional shift with the terrorist death toll moving towards Central and South America.

The terrorist organisations responsible for the most deaths in the region during the decade were the Shining Path of Peru, FMLN of El Salvador and the FDN of Nicaragua. These groups amongst others were either allied to a Communist ideology, backed by the former Soviet Union or were American backed groups.
The FDN of Nicaragua, for example, were part of the Contras (counter revolutionists), a collection of right-wing groups trained and funded by the American administration and according to the GTD responsible for an estimated 6662 deaths in the 1980s.
These groups were generally demobilised within approximately a decade in the backdrop of an ailing Soviet Union, which ultimately fell in 1991, thereby securing American geopolitical preeminence.
1990s
In the 1990s the terrorism death toll shifted again with the Tamil Tigers of Sri Lanka, Hutu extremists of Rwanda and the PKK being responsible for the most deaths.

The terrorist activities of the Tamil Tigers is rooted in the grievances that the Tamil minority had with the Sri Lankan government. Positive discrimination laws, for example in education, where university placements were weighted towards the Sinhalese majority irrespective of performance, creating a view amongst the Tamils that they were being marginalised. Thus a sectarian divide amongst these communities were amplified in terms of ethnic, language and religious differences (the Sinhalese are primarily Buddhists and Tamils predominantly Hindu). The conflict finally came to an end in 2009 with the Tamil Tigers acknowledging defeat following an overwhelming government military offensive.
Whilst the GTD leaves the motive as unknown for the vast majority of ‘Hutu extremist’ related terrorist deaths, these killings took place in the backdrop of the Rwandan genocide, a mass slaughter of Tutsis committed by the Hutu led Rwandan government, killing an estimated 800,000 people over a hundred days in 1994 (BBC). As such the wider genocide related deaths are excluded from the GTD data as its dataset does not include State terrorism. The causal factors behind the conflict are rooted in historic ethnic differences rather than religious, given that both communities are from a Christian background.
The PKK (Kurdistan Workers’ Party) were formulated as a far-left organisation campaigning for Kurdish autonomy. The organisation has its root in Turkey suppressing the Kurdish language and culture in the late 1970s. The organisation is still currently active, although there has been several unsuccessful ceasefire attempts.
2000s
The 2000s takes us into the next phase of terrorism, in which extreme Muslim militants weaponise religion through non-normative interpretations of Islam and use it as a vehicle to pursue geo-political objectives. The most spectacular of which being 9/11, in which 3001 people were murdered in the US and Al-Qaeda cited as the culpable party by the GTD. Al-Qaeda were also responsible for deaths in Iraq, South Asia and Western Europe over the course of the decade. The background to the creation of Al-Qaeda is tragically ironic in that similar to Central/South America in the 1980s, it was the United States that facilitated a proxy war with the Soviet Union by funding and training rebel groups operating in Afghanistan.

Post 9/11, the vast majority of Al-Qaeda’s operations were in Iraq, nonetheless there were some significant terrorist atrocities that were committed in Western Europe and South Asia which were almost certainly Al-Qaeda inspired (see chart below).

Subsequent to 9/11, the American administration invaded Afghanistan and overthrew the Taliban replacing it with the Karzai administration. As such the Taliban became the non-state actor and has been responsible for over three thousand deaths over the decade.
The third most prominent group during the 2000s were the LRA (Lord’s Resistance Army) of Uganda, a group led by Joseph Kony, indicted for war crimes by the ICC including for rape, enlisting of children, enslavement, mass mutilation, murder, etc. Kony has been widely condemned as using the cover of Christianity as a mechanism to conceal his own self serving interests.
2010s
Finally we reach the 2010s, in which terrorist Muslim groups come to dominate death tolls. At the time of writing, with GTD data available to 2017, the top 3 are ISIS, Boko Haram and the Taliban and the scale of terrorism related deaths is also unprecedented.

The sheer brutality of ISIS is well recorded with crimes against humanity including rape, slavery, mass executions/beheadings, etc. ISIS is yet another terrorist organisation that gained ascendancy amidst the backdrop of American intervention, this time through the 2003 Iraq War, in which the UN was bypassed and false claims were made that the Iraqi regime had acquired nuclear weapons capabilities. The subsequent power vacuum opened the door for an Al-Qaeda inspired organisation to gain a foothold in the region and as such ISIS was born.
The Taliban related death toll is a continuation of the conflict with the American administration. The Afghanistan War currently stands as the longest in America’s entire history, overtaking the Vietnam War by some considerable margin.
The third on the list, Boko Haram, has allied itself with ISIS including rebranding itself as Islamic State of West Africa, is guilty of copycat crimes against humanity, macabre in their nature in their sheer disregard for the sanctity of life.
Future
Every decade has brought about change in the international terrorism landscape. Whilst prediction is fraught with complexity, it would not be unreasonable to assume that the landscape will change once more during the next few decades. Actions that will potentially drive outcomes will include the level of proxy war gaming that major powers engage in and the subsequent level of regional destabilisations. Also, with an international increase in a vicious cycle of inward tribalism seeking to ‘other’ different communities, if unchecked may also act as the fuel to fire further terrorist activity.