The Sunni-Shia Divide

Sectarian conflict is becoming entrenched in a growing number of Muslim countries and is threatening to fracture Iraq and Syria. Tensions between Sunnis and Shias, exploited by regional rivals Saudi Arabia and Iran, could reshape the future Middle East.

An ancient religious divide is helping fuel a resurgence of conflicts in the Middle East and Muslim countries. Struggles between Sunni and Shia forces have fed a Syrian civil war that threatens to transform the map of the Middle East, spurred violence that is fracturing Iraq, and widened fissures in a number of tense Gulf countries. Growing sectarian clashes have also sparked a revival of transnational jihadi networks that poses a threat beyond the region.

Islam’s schism, simmering for fourteen centuries, doesn’t explain all the political, economic, and geostrategic factors involved in these conflicts, but it has become one prism through which to understand the underlying tensions. Two countries that compete for the leadership of Islam, Sunni Saudi Arabia and Shia Iran, have used the sectarian divide to further their ambitions. How their rivalry is settled will likely shape the political balance between Sunnis and Shias and the future of the region, especially in Syria, Iraq, Lebanon, Bahrain, and Yemen.

Alongside the proxy battle is the renewed fervor of armed militants, motivated by the goals of cleansing the faith or preparing the way for the return of the messiah. Today there are tens of thousands of organized sectarian militants throughout the region capable of triggering a broader conflict. And despite the efforts of many Sunni and Shia clerics to reduce tensions through dialogue and counterviolence measures, many experts express concern that Islam’s divide will lead to escalating violence and a growing threat to international peace and security.

Sunni and Shia Muslims have lived peacefully together for centuries. In many countries it has become common for members of the two sects to intermarry and pray at the same mosques. They share faith in the Quran and the Prophet Mohammed’s sayings and perform similar prayers, although they differ in rituals and interpretation of Islamic law.

Shia identity is rooted in victimhood over the killing of Husayn, the Prophet Mohammed’s grandson, in the seventh century, and a long history of marginalization by the Sunni majority. Islam’s dominant sect, which roughly 85 percent of the world’s 1.6 billion Muslims follow, viewed Shia Islam with suspicion, and extremist Sunnis have portrayed Shias as heretics and apostates.

Sunni Shia Muslim Population Graphic

Source: Pew Research, The Future of the Global Muslim Population, 2011

A regional war in the Middle East draws ever closer.

UN Independent International Commission of Inquiry on the Syrian Arab Republic

Origins of the Schism

Mohammed unveiled a new faith to the people of Mecca in 610. Known as Islam, or submission to God, the monotheistic religion incorporated some Jewish and Christian traditions and expanded with a set of laws that governed most aspects of life, including political authority. By the time of his death in 632, Mohammed had consolidated power in Arabia. His followers subsequently built an empire that would stretch from Central Asia to Spain less than a century after his death. But a debate over succession split the community, with some arguing that leadership should be awarded to qualified individuals and others insisting that the only legitimate ruler must come through Mohammed’s bloodline.

A group of prominent early followers of Islam elected Abu Bakr, a companion of Mohammed, to be the first caliph, or leader of the Islamic community, over the objections of those who favored Ali ibn Abi Talib, Mohammed’s cousin and son-in-law. The opposing camps in the succession debate eventually evolved into Islam’s two main sects. Shias, a term that stems from shi’atu Ali, Arabic for “partisans of Ali,” believe that Ali and his descendants are part of a divine order. Sunnis, meaning followers of the sunna, or “way” in Arabic, of Mohammed, are opposed to political succession based on Mohammed’s bloodline.

Ali became caliph in 656 and ruled only five years before he was assassinated. The caliphate, which was based in the Arabian Peninsula, passed to the Umayyad dynasty in Damascus and later the Abbasids in Baghdad. Shias rejected the authority of these rulers. In 680, soldiers of the second Umayyad caliph killed Ali’s son, Husayn, and many of his companions in Karbala, located in modern-day Iraq. Karbala became a defining moral story for Shias, and Sunni caliphs worried that the Shia Imams—the descendants of Husayn who were seen as the legitimate leaders of Muslims (Sunnis use the term “imam” for the men who lead prayers in mosques)—would use this massacre to capture public imagination and topple monarchs. This fear resulted in the further persecution and marginalization of Shias.

Even as Sunnis triumphed politically in the Muslim world, Shias continued to look to the Imams—the blood descendants of Ali and Husayn—as their legitimate political and religious leaders. Even within the Shia community, however, there arose differences over the proper line of succession. Mainstream Shias believe there were twelve Imams. Zaydi Shias, found mostly in Yemen, broke off from the majority Shia community at the fifth Imam, and sustained imamate rule in parts of Yemen up to the 1960s. Ismaili Shias, centered in South Asia but with important diaspora communities throughout the world, broke off at the seventh Imam. Most Ismailis revere the Aga Khan as the living representative of their Imam. The majority of Shias, particularly those in Iran and the eastern Arab world, believe that the twelfth Imam entered a state of occultation, or hiddenness, in 939 and that he will return at the end of time. Since then, “Twelvers,” or Ithna Ashari Shias, have vested religious authority in their senior clerical leaders, called ayatollahs (Arabic for “sign of God”).  

Many Christian, Jewish, and Zoroastrian converts to Islam chose to become Shia rather than Sunni in the early centuries of the religion as a protest against the ethnic Arab empires that treated non-Arabs as second-class citizens. Their religions influenced the evolution of Shia Islam as distinct from Sunni Islam in rituals and beliefs.    

Sunnis dominated the first nine centuries of Islamic rule (excluding the Shia Fatimid dynasty) until the Safavid dynasty was established in Persia in 1501. The Safavids made Shia Islam the state religion, and over the following two centuries they fought with the Ottomans, the seat of the Sunni caliphate. As these empires faded, their battles roughly settled the political borders of modern Iran and Turkey by the seventeenth century, and their legacies resulted in the current demographic distribution of Islam’s sects. Shias comprise a majority in Iran, Iraq, Azerbaijan, and Bahrain, and a plurality in Lebanon, while Sunnis make up the majority of more than forty countries from Morocco to Indonesia.

Modern Tensions

Iran’s Islamic Revolution in 1979 gave Shia cleric Ayatollah Ruhollah Khomeini the opportunity to implement his vision for an Islamic government ruled by the “guardianship of the jurist” (velayat-e faqih), a controversial concept among Shia scholars that is opposed by Sunnis, who have historically differentiated between political leadership and religious scholarship. Shia ayatollahs have always been the guardians of the faith. Khomeini argued that clerics had to rule to properly perform their function: implementing Islam as God intended, through the mandate of the Shia Imams.

Under Khomeini, Iran began an experiment in Islamic rule. Khomeini tried to inspire further Islamic revival, preaching Muslim unity, but supported groups in Lebanon, Iraq, Afghanistan, Bahrain, and Pakistan that had specific Shia agendas. Sunni Islamists, such as the Muslim Brotherhood and Hamas, admired Khomeini’s success, but did not accept his leadership, underscoring the depth of sectarian suspicions.

Saudi Arabia has a sizable Shia minority of roughly 10 percent, and millions of adherents of a puritanical brand of Sunni Islam known as Wahhabism (an offshoot of the Sunni Hanbali school) that is antagonistic to Shia Islam. The transformation of Iran into an overtly Shia power after the Islamic revolution induced Saudi Arabia to accelerate the propagation of Wahhabism, as both countries revived a centuries-old sectarian rivalry over the true interpretation of Islam. Many of the groups responsible for sectarian violence that has occurred in the region and across the Muslim world since 1979 can be traced to Saudi and Iranian sources.

Saudi Arabia backed Iraq in the 1980–1988 war with Iran and sponsored militants in Pakistan and Afghanistan who were primarily fighting against the Soviet Union, which had invaded Afghanistan in 1979, but were also suppressing Shia movements inspired or backed by Iran.

The transformation of Iran into an agitator for Shia movements in Muslim countries seemed to confirm centuries of Sunni suspicions that Shia Arabs answer to Persia. Many experts, however, point out that Shias aren’t monolithic—for many of them, identities and interests are based on more than their confession. Iraqi Shias, for example, made up the bulk of the Iraqi army that fought Iran during the Iran-Iraq War, and Shia militant groups Amal and Hezbollah clashed at times during the Lebanese civil war. The Houthis, a Zaydi Shia militant group in Yemen, battled the government of Ali Abdullah Saleh, a Zaydi, several times between 2004 and 2010. Then, in 2014, the Houthis captured the capital Sana'a with ousted president Saleh's support.

Percent of Sunnis who accept Shias as Muslim Infographic

Source: Pew Research, The World’s Muslims: Unity and Diversity, 2012

For their part, both mainstream and hard-line Sunnis aren’t singularly focused on oppressing Shias. They have fought against coreligionists throughout history, most recently in the successive crackdowns on the Muslim Brotherhood in Egypt, Iraq’s 1990 invasion of Kuwait, and Saudi Arabia’s battles against al-Qaeda and related Sunni militant groups. Sharing a common Sunni identity didn’t eliminate power struggles among Sunni Muslims under secular or religious governments.

But confessional identity has resurfaced wherever sectarian violence has taken root, as in Iraq after the 2003 U.S.-led invasion removed Saddam Hussein, a dictator from the Sunni minority who ruled over a Shia-majority country. The bombing of a Shia shrine in Samara in 2006 kicked off a cycle of sectarian violence that forced Iraqis to pick sides, stirring tensions that continue today.

In the Arab world, Shia groups supported by Iran have recently won important political victories. The regime of Bashar al-Assad, which has ruled since 1970, relies on Alawis, a heterodox Shia sect that makes up about 13 percent of Syria’s population, as a pillar of its power. Alawis dominate the upper reaches of the military and security services in Syria and are the backbone of the forces fighting to support the Assad regime in Syria’s civil war. Since the 2003 invasion of Iraq unseated Saddam Hussein and instituted competitive elections, the Shia majority has dominated the parliament and produced its prime ministers. Hezbollah, the Lebanese Shia militia and political movement, is the strongest political actor in Lebanon. Shia militants in Yemen, tenuously linked to Iran, have become the country's dominant power. Iran’s regional influence has swelled as its allies in these countries have accumulated power.

Sunni governments, especially Saudi Arabia, have increasingly worried about their own grips on power, a concern that was exacerbated with the protest movement that began in Tunisia in late 2010. The Arab Awakening, as the uprisings are known, spread to Bahrain and Syria, countries at the fault lines of Islam’s sectarian divide. In each, political power is held by a sectarian minority—Alawis in Syria, where Sunnis are the majority, and a Sunni ruling family in Bahrain, where Shias are the majority. The civil war in Syria, which is a political conflict at its core, has exposed sectarian tensions and become the staging ground for a vicious proxy war between the region’s major Sunni and Shia powers. In Yemen, Houthi rebels have expanded their territory south of Saudi Arabia, providing Iran a potential beachhead along the strategic shipping routes in the Red Sea. Some analysts view the Syrian conflict as the last chance for Sunnis to limit and reverse the spread of Iranian power and Shia influence in the Arab world.

Practicing the Faith

Sunnis and Shias agree on the basic tenets of Islam: declaring faith in a monotheistic God and Mohammed as his messenger, conducting daily prayers, giving money to the poor, fasting during the Muslim holy month of Ramadan, and performing the pilgrimage to Mecca.

There are divisions even over the precepts of Islam, but the main difference relates to authority, which sparked the political split in the seventh century and evolved into divergent interpretations of sharia, or Islamic law, and distinct sectarian identities.

Shias believe that God always provides a guide, first the Imams and then ayatollahs, or experienced Shia scholars who have wide interpretative authority and are sought as a source of emulation. The term “ayatollah” is associated with the clerical rulers in Tehran, but it’s primarily a title for a distinguished religious leader known as a marja, or source of emulation. Iran’s supreme leader, Ali Khamenei, was appointed by an elected body of Iranian clerics, while maraji (plural of marja) are elevated through the religious schools in Qom, Najaf, and Karbala. Shias can choose from dozens of maraji, most of whom are based in holy cities in Iraq and Iran. Many Shias emulate a marja for religious affairs and defer to Supreme Leader Ali Khamenei in Iran for political guidance. For Sunnis, authority is based on the Quran and the traditions of Mohammed. Sunni religious scholars, who are constrained by legal precedents, exert far less authority over their followers than their Shia counterparts.

Both sects have subdivisions. The divisions among Shias were discussed above. Four schools comprise Sunni jurisprudence: Hanafi, Shafii, Maliki, and Hanbali, the latter spawning the Wahhabi and Salafi movements in Saudi Arabia. Sunnism, a broad umbrella term for non-Shia Islam, is united on the importance of the Quran and practice of Mohammed but allows for differences in legal opinion.

Dear Karbala, dear Najaf, dear Kadhimiyah, and dear Samarra, we warn the great powers and their lackeys and the terrorists, the great Iranian people will do everything to protect them.

Iranian president Hassan Rouhani

Sectarian Militants

Communal violence between Islam’s sects has been rare historically, with most of the deadly sectarian attacks directed by clerics or political leaders. Extremist groups, many of which are fostered by states, are the chief actors in sectarian killings today.

The two most prominent terrorist groups, Sunni al-Qaeda and Shia Hezbollah, have not defined their movements in sectarian terms, and have favored using anti-imperialist, anti-Zionist, and anti-American frameworks to define their jihad, or struggle. They share few similarities beyond the use of violence. Hezbollah has developed a pragmatic political wing that competes in elections and is part of the Lebanese government, a path not chosen by al-Qaeda, which operates a diffuse network largely in the shadows. Both groups have deployed suicide bombers, and their attacks shifted from a focus on the West and Israel to other Muslims, such as al-Qaeda’s killing of Shia civilians in Iraq and Hezbollah’s participation in the Syrian civil war.

Conflict and chaos have played a role in the reversion to basic sectarian identity. In Iraq, for instance, remnants of the Ba’athist regime employed Sunni rhetoric to mount a resistance to the rise of Shia power following the ouster of Saddam. Sunni fundamentalists, many inspired by al-Qaeda’s call to fight Americans, flocked to Iraq from Muslim countries, attacking coalition forces and many Shia civilians. Abu Musab al-Zarqawi, who founded al-Qaeda’s franchise in Iraq, evoked ancient anti-Shia fatwas, or religious rulings, to spark a civil war in hopes that the Shia majority would eventually capitulate in the face of Sunni extremist violence. The Shia community absorbed thousands of deaths before fighting back with their own sectarian militias.

Syria’s civil war, which exceeded the casualty toll of Iraq’s decade-long conflict in its first three years, has amplified sectarian tensions to unprecedented levels. The war began with peaceful protests in 2011 calling for an end to the Assad regime, which has ruled since 1970. The Assad family and other Alawis have stirred resentment by Syria’s majority Sunnis after decades of repression and a sectarian agenda that elevated minority Alawis in government and the private sector. The 2011 protests and brutal government crackdown uncovered sectarian tensions in Syria, which have rippled across the region.

Tens of thousands of Syrian Sunnis joined rebel groups such as Ahrar al-Sham, the Islamic Front, and al-Qaeda’s Nusra Front, which all employ anti-Shia rhetoric; similar numbers of Syrian Shias and Alawis enlisted with an Iran-backed militia known as the National Defense Force to fight for the Assad regime. Foreign Sunni fighters from Arab and Western countries joined the rebels, while Lebanon’s Hezbollah and some Shia militias from Iraq such as Asaib Ahl al-Haq and Kata'ib Hezbollah backed the Syrian government. Even Afghan Shia refugees in Iran have reportedly been recruited by Tehran for the war in Syria, pitting them against Sunni foreign fighters who may have forced the Afghans into exile decades earlier. Syria’s civil war has attracted more militants from more countries than were involved in the conflicts in Afghanistan, Chechnya, and Bosnia combined.

Al-Qaeda in Iraq, decimated by the “Awakening” of Sunni Iraqis who joined the fight against extremists, the U.S.-led military surge, and the death of Zarqawi, found new purpose in exploiting the vacuum left by the receding Syrian state. It established its own transnational movement known as the Islamic State in Iraq and Syria (ISIS). The group expanded its grip on Sunni provinces in Iraq and eastern regions in Syria, seizing Iraq’s second-largest city, Mosul, in June 2014. It defied orders from al-Qaeda’s top commanders to curtail its transnational ambitions and extremism, which led to ISIS’s expulsion from al-Qaeda in February 2014. ISIS rebranded as the Islamic State in July 2014 and declared its leader, Abu Bakr al-Baghdadi, as caliph. The group's highly publicized killing of Western hostages triggered a campaign of air strikes by the United States and its regional allies Jordan, Qatar, Saudi Arabia, and the United Arab Emirates.

Extremist groups have come to rely on satellite television and high-speed Internet over the past two decades to spread hate speech and rally support. Fundamentalist Sunni clerics, many sponsored by wealthy Sunnis from Saudi Arabia and the Gulf states, have popularized anti-Shia slurs. Shia religious scholars have also taken to the airwaves, mocking and cursing the first three caliphs and Aisha, one of Mohammed’s wives.

Sectarian rhetoric dehumanizing the “other” is centuries old. But the volume is increasing. Dismissing Arab Shias as Safawis, a term that paints them as Iranian agents (from the Safavid empire) and hence traitors to the Arab cause, is increasingly common in Sunni rhetoric. Hard-line Sunni Islamists have used harsher historic terms such as rafidha, rejecters of the faith, and majus, Zoroastrian or crypto Persian, to describe Shias. Iranian officials, Iraq’s prime minister, and Hassan Nasrallah, the leader of Hezbollah, routinely describe their Sunni opponents as takfiris (code for al-Qaeda terrorists) and Wahhabis. This cycle of demonization has been exacerbated throughout the Muslim world.

For Sunni extremists, new technologies and social-media channels have revolutionized recruitment opportunities. Fundamentalists no longer have to infiltrate mainstream mosques and attract recruits surreptitiously, but can now disseminate their call to jihad and wait for potential recruits to contact them. These channels aren’t as useful for recruiting Shia militants, who benefit from state support in Syria, Iraq, and Iran, and can openly advertise their calls for sectarian jihad.

The Sunni-Shia Divide

Terrorist violence in 2013 was fueled by sectarian motivations, marking a worrisome trend, in particular in Syria, Lebanon, and Pakistan.

U.S. Department of State

Flash Points

Sunni-Shia tensions contribute to multiple flash points in Muslim countries that are viewed as growing threats to international peace and security. The following arouse the most concern among regional specialists:

Rising Militancy

Notable concern about the role of sectarian violence increased in 2013. Extremists were “fueled by sectarian motivations” in Syria, Lebanon, and Pakistan, according to the U.S. State Department. After years of steady losses for al-Qaeda–linked groups, Sunni extremist recruitment is rising, aided by private funding networks in the Gulf, particularly in Kuwait, with much of the violence directed at other Muslims rather than Western targets. Shia militants are also gaining strength, in part to confront the threat of Sunni extremism, miring many Muslim communities in a vicious cycle of sectarian violence.

U.S. officials such as FBI director James B. Comey have warned that the war in Syria, which attracted thousands of fighters from Europe and the United States, poses a long-term threat to Western interests. The eventual outflow of these militants, battle-hardened and with Western passports, is viewed as a potential “terrorist diaspora” that could eclipse the global terror networks that emerged after the Afghan war against the Soviet Union in the 1980s.

Saudi-Iranian Rivalry

Saudi Arabia and Iran have deployed considerable resources to proxy battles, especially in Syria, where the stakes are highest. Riyadh closely monitors potential restlessness in its oil-rich eastern provinces, home to its Shia minority, and has deployed forces along with other Gulf countries to suppress a largely Shia uprising in Bahrain. It also assembled a coalition of ten Sunni-majority countries, backed by the United States, to reverse the growing influence of Houthis in Yemen. Saudi Arabia provides hundreds of millions of dollars in financial support to the predominantly Sunni rebels in Syria, while simultaneously banning cash flows to al-Qaeda and extremist jihadi groups fighting the Assad regime. 

Iran has allocated billions of dollars in aid and loans to prop up Syria’s Alawi-led government, and has trained and equipped Shia militants from Lebanon, Iraq, Syria, and Afghanistan to fight with various sectarian militias in Syria. At the same time, the widening proxy battle may also be stirring concern among leaders in Riyadh and Tehran about the consequences of escalation. The two sides have repeatedly postponed efforts to establish a dialogue for settling disputes diplomatically. Iran is fighting the Islamic State in parts of Iraq, while Saudi Arabia and other Sunni-majority countries joined a U.S.-led air campaign against the extremist group in Syria and Iraq.

Humanitarian Crisis

The ongoing civil war in Syria has displaced millions internally, and almost three million civilians, mostly Sunni, are now refugees in Lebanon, Jordan, Iraq, and Turkey. The influx of more than a million Syrians into Lebanon, a state with a historically combustible religious mix that experienced its own fifteen-year civil war in the 1970s and 1980s, has burdened its cash-strapped government and pressured communities hosting refugees. Jordan and Iraq are still struggling to provide housing and services to an impoverished and traumatized population. Turkey has the greatest capacity to provide humanitarian aid, yet Ankara must increasingly balance “the public’s sympathy for and unease toward refugees,” the International Crisis Group reports.

Fractured States

Syria’s civil war, as well as Iraq’s sectarian conflict, is threatening to redraw the map of the Middle East bequeathed to the region by British and French colonial authorities. The Assad regime in Syria has consolidated control over the Mediterranean coast, the capital of Damascus, and the central city of Homs, which together comprise a rump state that connects with Hezbollah strongholds, threatening the territorial integrity of Lebanon. Other parts of the country are contested or controlled by various rebel and Islamist groups, including ISIS, which seeks to dominate the eastern regions of Syria that link to its territory in Iraq. And Kurdish groups in northern Syria, which, like their Iraqi cousins, have long campaigned for basic rights denied under the Ba'athist government, are on the verge of gaining de facto independence. Yemen, which was unified in 1990, is at risk of re-fracturing into two countries, largely along sectarian lines.

The United States spent more than one trillion dollars to stabilize Iraq, but the country remains in a precarious state. Sectarian tensions are mounting in Iraq as the newly ascendant Shia majority struggles to accommodate the Sunni minority and deal with the Kurdish Regional Government in the north of the country while confronting extremist Sunni groups. Most politicians and activists in Iraq, Syria, and Lebanon reject attempts to redraw the map of the region, but the vanishing borders and emergence of new areas of influence based on sectarian and ethnic identities are a growing existential challenge.

Sunnis had no other option but to defend themselves and use arms. We reached a point of to be or not to be.

Tariq al-Hashimi, former vice president of Iraq



Geneive Abdo

Fellow, Middle East Program, Stimson Center

Deborah Amos

Middle East Correspondent, National Public Radio

Reza Aslan

Associate Professor, University of California, Riverside

F. Gregory Gause III

Senior Fellow, Brookings Doha Center

Bruce Hoffman

Director, Center for Security Studies, Georgetown University

Ed Husain

Adjunct Senior Fellow for Middle Eastern Studies, CFR

Vali R. Nasr

Dean, School of Advanced International Studies, Johns Hopkins University


Current Tensions

The Sistani Factor (August 2014)

NYU professor Mohamad Bazzi explores the political role of Shia clerics in Iraq and Iran.

The Roots and Future of Sectarianism in the Gulf (March 2014)

Frederic Wehrey of the Carnegie Endowment explains the limits of analyzing conflicts solely through the Sunni-Shia prism, with a focus on sectarianism in the Gulf.

Iran’s Foreign Minister Snubs a Saudi Invite (June 2014)

Brookings senior fellow Suzanne Maloney explores Iran-Saudi relations.

Saudi Arabia’s Hidden Uprising (May 2014)

Saudi Arabia has largely suppressed a Shia uprising in the kingdom, according to this BBC report.

Syria’s Uprising Within an Uprising (January 2014)

Sunni rebels in Syria are fighting against their coreligionists from ISIS, complicating the sectarian fault lines of Syria’s civil war, explains Rania Abouzeid of the European Council on Foreign Relations.

Rise of Sunni Foreign Fighters in Syria (December 2013)

Foreign fighters in Syria, especially Sunnis with Western passports, are a looming risk for many countries. Aaron Zelin of the Washington Institute for Near East Policy tracks the rise of foreign Sunni fighters.

Iran-backed Shia Militias Flock to Syria (March 2014)

The Guardian reports on the involvement of Iraqi Shia militias in Syria’s war.

Bahrain’s Fake Sectarian War (June 2013)

Reza Aslan explains in this 2013 Foreign Affairs essay how Bahrain exploited the kingdom’s sectarian divide to discredit a nonsectarian uprising for greater political freedom.

The New Sectarianism (April 2013)

Geneive Abdo of the Brookings Institution uses Lebanon and Bahrain as case studies to explore heightened Sunni-Shia tensions following the “Arab Awakening” protests of 2011.

Iraq’s Sunnis and the State (August 2013)

Iraq’s Sunnis have grown frustrated with the political process, and the Shia government’s crackdown on peaceful protests have rekindled a Sunni insurgency, the International Crisis Group explains in this 2013 report.

The Shiite Jihad in Syria and Its Regional Effects (February 2015)

Phillip Smyth charts the rise of Iran-funded militias in Syria following the uprising against the Assad regime in this Washington Institute for Near East Policy paper.


Islam: Sunni and Shiites (January 2009)

The nonpartisan Congressional Research Service reviews the basics of the Sunni-Shia divide.

When the Shiites Rise (July 2006)

Vali Nasr explains how the toppling of Saddam Hussein in Iraq helped launch a Shia revival in the country and the Middle East in this Foreign Affairs article. Nasr expands on the roots of the Sunni-Shia divide in his 2007 book "The Shia Revival: How Conflicts within Islam Will Shape the Future."

Across the Arab World, a Widening Rift (February 2007)

Evidence of simmering sectarian tensions is examined in this sweeping report on the region by the late Middle East correspondent Anthony Shadid.

The Partisans of Ali (February 2007)

This five-part NPR series explores the Sunni-Shia divide.

Mapping the Global Muslim Population (October 2009)

This demographic study by Pew Research maps the global Muslim population. Pew also studies Sunni and Shia attitudes, and its 2012 poll shows that many Muslims worry about religious conflict.

Can You Tell a Sunni from a Shiite? (October 2006)

Many U.S. counterterrorism officials struggle to explain the differences between Sunnis and Shias in this New York Times article.

Sectarian Militants

Apocalyptic Prophecies Motivate Shia and Sunni Fighters (April 2014)

Shia and Sunni fighters around the world use end-times prophecies to justify their involvement in the wars in Iraq and Syria, Mariam Karouny of Reuters reports.

Lebanon’s Hezbollah Turns Toward Syria (May 2014)

The International Crisis Group examines Hezbollah’s involvement in the Syrian civil war.

Iraqi Fighters in Syria’s Shia Militias (August 2013)

This CTC Sentinel article explores the regional expansion of Iraqi Shia militias into Syria.

Iran’s Shadow Commander (September 2013)

The New Yorker’s Dexter Filkins profiles Qassem Suleimani, an Iranian commander in charge of his country’s proxy war efforts in Iraq and Syria.

Al-Qaeda: A Persistent Threat (2014)

The RAND Corporation tracks the evolution of al-Qaeda and other Salafi groups and assesses the threats posed by various affiliates.

The ISIS Battle Plan (June 2014)

The Institute for the Study of War examines ISIS battle plans in Iraq. The Washington-based think tank has published many reports on ISIS and monitors the group's evolution in Iraq and Syria.


These discussion questions, essay questions, activities and assignments, and supplementary resources are designed to help educators use “The Sunni-Shia Divide” InfoGuide in the classroom through an active, learner-centered approach.

Discussion Questions

Ideas for questions to use in facilitating full-class discussions, assigning small group discussion topics, or posting on a class discussion board. Questions allow students to critically reflect on the material provided in the InfoGuide and hone their communication skills.

Essay Questions

Suggestions for essay topics that enable students to dive deeper into the material found in the InfoGuide and conduct their own research and analysis.

Activities and Assignments

In-class activity ideas and homework assignments based on “The Sunni-Shia Divide” that promote participatory learning and critical thinking. These can be adapted based on students’ levels and classroom needs. For high school teachers, these activities are accompanied by a list and description of the Common Core State Standards they meet.

Further Reading

The Sistani Factor (August 2014)

NYU professor Mohamad Bazzi explores the political role of Shia clerics in Iraq and Iran.