The two great branches of Islam coexist in Iraq across linguistic and ethnic groups. There are Sunni Arabs and Shiite Arabs, Sunni Kurds and (a tiny minority of) Shiite Kurds. Arabs are a linguistic group, speaking a Semitic language. Kurds speak and Indo-European language related to English.
Sunnism and Shiism as we know them have evolved over nearly a millennium and a half. But the difference between them begins after the death of the Prophet Muhammad in 632 AD (CE) in the city-state of Mecca in western Arabia. Muhammad, the son of Abdallah, had derived from the noble Quraysh clan. Those who became the Shiites insisted he should be succeeded by Ali, his cousin and son-in-law (and the next best thing to a living son). This dynastic principle was rejected by the group that became the Sunnis. They turned for leadership to prominent notables of the Quraysh, whom they saw as caliphs or vicars of the Prophet. The first three caliphs had given their daughters in marriage to the Prophet and so were his in-laws, but Sunni principles said that they needn’t have been– any prominent, pious male of the Quraysh would have done.
There is a vague analogy to the split between Catholicism and Protestantism, on the difference between seeing Peter as the foundation of the Church and of seeing Paul as that.
Iraq was part of the medieval caliphates– the Orthodox Caliphs, then the Umayyad Arab kingdom, and then the Abbasids. In 1258 the invading Mongols (themselves Buddhists and animists) sacked Baghdad and executed the last caliph. It is said that they were warned that it was very bad luck to shed the blood of a caliph, so they rolled him up in a Persian rug and beat him to death with hammers.
Parts of what is now Iraq were ruled by the Mongol Il Khanid state (which gradually became Muslim), and then by fragmented small principalities until the rise of the two great Middle Eastern empires of the early modern period, the Safavid and the Ottoman. The Safavids, based in Iran, were Shiites and ruled Baghdad 1508-1534. Then the Ottomans, Sunnis based in what is now Turkey, took Iraq in 1534 and ruled it, with the exception of a couple of decades of Iranian reassertion, until World War I.
The elite of Iraq was Sunni since the medieval period, though there were always significant Shiite movements. In the course of the late 18th and the nineteenth centuries, under Ottoman rule, the tribes of the south of Iraq gradually converted to Shiite Islam. This may have been a form of protest against Ottoman oppression. It was in part influence from wealthy Shiite states in India after the fall of the Mughal Empire in the 1700s and before the imposition of British direct rule over all of North India from 1856. The Indian Shiite potentates or Nawabs gave money for the building of water canals out to the shrine cities of Najaf and Karbala in Iraq, which suffered from lack of water. Once the canals were built, tribes irrigated off them and settled near the holy cities, the residents of which proselytized them into Shiism.
The elites of Mosul and Baghdad, however, tied to patronage from the Ottoman Sultan, resisted this conversion movement and remained Sunnis, recognizing the four Orthodox Caliphs. From about 1880, Ottoman Sultan Abdulhamid II started claiming to be a caliph, on the medieval model. This claim wasn’t universally accepted but it was popular among Muslims in colonized British India in particular. The British, French and Russians defeated the Ottomans in World War I, after which the empire collapsed. In 1924 the new secular Republic of Turkey under Mustafa Kemal Attaturk abolished the caliphate. Sunnis became like Protestants, organized by country and lacking a central node of authority. Some fundamentalist Sunnis refused to accept this situation and dreamed of reconstituting the caliphate as a center of authority that could unite 1.5 billion Muslims and deliver them from their divided estate and consequent weakness in the face of the West.
When the British took Iraq during World War I, after the Ottomans unwisely allied with Germany and Austria, they mainly turned to the Sunni elites as partners in building a new “Mandate” or colony recognized by the League of Nations. When the Iraqis revolted in 1920 against the prospect of British colonialism, desiring independent statehood instead, the British brought in Faisal as king. He was the son of Sharif Hussein of Mecca, and a Sunni, who had allied with the British (think Lawrence of Arabia) to revolt against the Ottomans during the war.
Faisal lacked roots in Iraq, and turned, in order to rule the country, to the Sunni mercantile and bureaucratic elites of Baghdad and Mosul. He also picked up the remnants of the Ottoman-trained officer corps to constitute his new military, almost all of the Sunnis (the Sunni Ottomans were skittish about 12er Shiite officers).
Although the Shiites were a majority in Iraq, Sunnis predominated in positions of power and wealth throughout the twentieth century. When the Baath Party, a secular, socialist and nationalist movement, came to power in 1968, it was dominated by Sunnis from the area north of Baghdad. The Baathists created a one-party state and repressed religious Shiites (and also religious Sunnis who mixed in politics). The high generals, bureaucrats, entrepreneurs and politicians were Sunni. There were Shiites in the Baath Party, but they had less status than the Sunnis. After the Gulf War of 1990-91 when the US and allies pushed Iraq back out of Kuwait, the Shiites of south Iraq rose up. The US had urged them to do so, but stood by while the Baath massacred the Shiites. The Shiite religious parties interpreted this spring 1991 repression as sectarian genocide. Belonging to the main Shiite religious party, the Da’wa (Call or Mission) Party, was made a capital crime by the Baath already in 1980 and members were often killed and put in mass graves.
In the 1990s when Iraq was under severe US and UN sanctions, some lived on smuggling oil and other goods out to Jordan. The Jordanian form of modern Sunni fundamentalism, or Salafism, made inroads into Iraq along truck stop towns like Fallujah and Ramadi. The Baath Party, although hostile, winked at this development because sanctions made it weak. At the same time, Baath leader Izzat Duri developed ties of patronage with the Naqshbandi Sufi order in Mosul. Sufism or Muslim mysticism is the opposite of fundamentalism, valuing rituals and saints and mystical experiences of God. Both Salafism and Sufism had a revival in the 1990s.
The US overthrew Saddam Hussein of the Baath Party in 2003 in alliance with Shiite groups primarily. Those Shiite groups wanted revenge on the disproportionately Sunni Baath Party. They carried out a program of “de-Baathification,” in which they fired tens of thousands of Sunni Arabs from their government jobs as bureaucrats and even teachers. They hired Shiite clients instead. The Neocons hated the state-owned industries, and closed them down as inefficient without putting anything in their place. The Bush administration backed Shiite supremacism and debaathification to the hilt. Its proponents likened it to de-Nazification after WW II in Germany, but actually former Nazis below the top level in Germany typically kept their jobs.
In the new Iraq, Sunni high status was turned upside down. The Sunnis had been the top graduates of the officer training academies, the equivalent of West Point. They disproportionately dominated the officer corps. They were at the top of the Baath Party. They were the rich entrepreneurs to whom lucrative government contracts were given. Now they were made unemployed, or given menial jobs, while the goodies went to the members of Shiite religious parties. Massive unemployment swept the Sunni cities in 2003-2004.
In 2005 the US was maneuvered by Grand Ayatollah Ali Sistani and his allies, all Shiites, into having parliamentary elections. Because of the US military attack on Sunni Fallujah, the Sunnis of Mosul, Ramadi and elsewhere boycotted that election. Sistani had insisted that the parliament also function as a constituent assembly to draft the constitution. There were almost no Sunnis in the first 2005 parliament, so the constitution was crafted by the Shiites and the Kurds. They Sunnis rejected it in their provinces by a solid majority (by 2/3s in two provinces).
Sunnis all along were nervous about the Shiite-Kurdish government erected under the Americans and some turned to guerrilla warfare. When guerrillas blew up the Golden Dome shrine in Samarra in February 2006, a site sacred to Shiites, it kicked off a civil war. In summer of 2006 3000 people were being killed a month. Shiite militias ethnically cleansed Sunnis from mixed neighborhoods in Baghdad. When Gen. Petraeus conducted his troop escalation (‘surge’), he disarmed the Sunni militias first, inadvertently leaving Sunnis in the capital vulnerable to threats and night raids. The Sunnis ran away to Syria and Jordan or to Mosul. After a while there were few mixed neighborhoods and it was harder for Shiites and Sunnis to get at one another, so the violence subsided.
In the one-chamber Iraqi parliament, Sunnis would always be a minority. When they stopped boycotting they typically got 56 seats. The Shiites and Kurds typically allied against them so that they lost all important votes. In 2010, they united behind the Iraqiya Party of ex-Baathist Ayad Allawi, which became of the largest single party in parliament, with 91 seats. But Allawi could not find Shiite or Kurdish allies to bring his total up to 51% and so could only have headed a minority government open to being toppled at any time by a vote of no confidence. In contrast Nouri al-Maliki of the Da’wa Party put together, with Iran’s help, a Shiite majority and allied with the Kurds for a super-majority. President Jalal Talabani therefore appointed al-Maliki to a second term.
Secular groups like the 1920 Revolution Brigades and the Army of Muhammad, and Sufi ones like the Men of the Naqshbandiya, formed cells to fight the American occupation. Another of the Sunni insurgent groups was al-Qaeda in Mesopotamia, led by the Jordanian Abu Musab al-Zarqawi. He was killed in 2006, but it made no difference to the movement, which continued to blow things up. When US military officers in the field in 2005 tried to reach out to disaffected Sunni tribes, Condi Rice is said to have stopped them, lest Washington offend its Shiite allies in Baghdad. Al-Qaeda in Mesopotamia later started styling itself the Islamic State of Iraq. It engaged in extensive terrorist operations in a bid to stop the new Shiite-dominated government from establishing itself. When the revolution in Syria turned violent in late 2011, its fighters went there and the organization became the Islamic State of Iraq and Syria (or Iraq and the Levant). It is said to have received money from rich private businessmen in Kuwait who support the fundamentalist Salafi form of Sunni Islam, and which typically hates Shiites. ISIS became the best fighters and they captured Syrian Baath military bases and took towns like Raqqa and Aleppo neighborhoods.
From 2011 when there was a ‘Sunni Arab Spring’ in Iraq, with urban youth demonstrations and demands for an end to discrimination, the al-Maliki government heavy-handedly repressed it. If it instead had accommodated those moderate young people in their demands, it might have avoided losing the Sunni areas to religious extremists.
In the 2014 elections, the Sunnis did poorly and it was clear that they would continue to be marginalized in parliament by Shiites and Kurds. The Shiite-dominated government provided them with few services or jobs. Although Iraq is an oil state, you can’t tell it. I was in Baghdad last year this time and it was dowdy and nothing like Abu Dhabi or Dubai. In Mosul, residents complained of electricity outages and lack of services or jobs. Shiite troops often put up Shiite insignia to humiliate Sunnis. They frisked Sunnis at checkpoints. Sunnis felt as though they were frozen out of meaningful power and treated as though under Shiite occupation. This situation derived in part from the invidious Bush policies of backing the Shiites against the Sunnis.
ISIS, having gained fighting experience and a taste of urban administration in Syria, expanded its cells back in Fallujah, Ramadi and Mosul in western and northern Iraq. Last January it took over Fallujah and parts of Ramadi west of Baghdad. Last week it took over Mosul and most other towns in Ninevah Province. This was not primarily a military conquest but a coordinated urban uprising against Iraqi security forces, in coordination with other Sunni groups, including secular ex-Baathists. ISIS also tried to advance into Salahuddin and Diyala Provinces, though it seems to have been checked there by the Iraqi army and Sunni tribal and urban allies. At the moment, ISIS is a force in al-Anbar and Ninevah Provinces, which are mostly Sunni Arab. But they are demographically vastly outnumbered by the Kurds and Shiites, who could well riposte militarily.
Sunni Iraqis had been in the 20th century cosmopolitan and often modernists. Many were liberals yearning for democracy. From 1968 they turned to more of a Soviet model, a strongly secular one. They have turned in desperation to rural fundamentalists who want a medieval caliphate only because of the vast reversal in their fortunes resulting from the Bush invasion and occupation, and the unfair policies of the Shiite government, which has turned them from an elite into an underclass. They are capable, trained, educated people. They aren’t going to put up with that, and if turning to al-Qaeda is the only way to avoid that fate, they are often willing now to do it.