Iraq's population includes most of the Middle East's religions, ethnic groups and cultures, a diversity that many hope will one day become an example of harmony for a hate-riven region.
Now, Iraq's first burst of freedom threatens to open a season of jockeying for power, revenge and score-settling that might preoccupy the United States as much as providing humanitarian relief and putting together a new government that represents the aspirations of all Iraqis.
"How these groups will live with one another in a postwar environment, and how something can be arranged that satisfies all of them, is a daunting prospect," said Amy Hawthorne of the Carnegie Endowment for International Peace, who specializes in political change in the Arab world.
While trying to quell or prevent internal flare-ups, the United States will also have to ease the anxieties of Iraq's neighbors, who fear the impact of Iraqi turbulence on their populations.
"All of this creates real challenges, but they don't necessarily have to be insurmountable," said Kenneth Pollack of the Brookings Institution's Saban Center for Middle East Policy.
The oil-rich cities of Kirkuk and Mosul are of particular concern. Turkish leaders fear that if Kurds were to gain control of those cities, they would have a strong economic base for an independent Kurdistan. Turkey threatened to send troops to the region if Kurds were allowed to take control of Kirkuk and Mosul. Turkey also feels protective toward the sizable, ethnically-related Turkoman minority concentrated in and around the two cities.
Iraq's ethnic makeup includes Arabs, Kurds, Turkomen, Assyrians, Circassians and Azeris. Its population breaks down along religious lines to includes Shiite and Sunni Muslims, Christians and a small number of Jews, and is further subdivided among competing tribes.
Even during the days of the Ottoman Empire, which collapsed in World War I, much of the region that Iraq occupies today was dominated by the Sunni Muslim minority, denying majority Shiites a representative share of power. During his 24-year rule, Saddam Hussein enforced this dominance with brutal repression.
Now that Hussein's yoke has been lifted, looters from Saddam City, an impoverished Baghdad Shiite slum, have emerged to ransack the abandoned homes of regime leaders.
Between Shiites and Sunnis, "there's a potential for score-settling that's been repressed for 80 years," said Pollack.
Regional specialists say there is also a strong potential for revenge against members of the Baath Party that has ruled the country since the late 1960s, or against Hussein's network of supporters and those who became rich thanks to the regime - whatever their religion.
It was apparently in an attempt to avoid such a possibility that Abdul Majid al-Khoei, a moderate and respected Shiite cleric returning from exile in London, met his death yesterday in the Iraqi holy city of Najaf. According to accounts from the scene, al-Khoei had accompanied Haider al-Kadar, a hated official in Saddam's Ministry of Religion, to a Muslim shrine in a gesture of reconciliation. Al-Khoei pulled a gun after an angry crowd turned on al-Kadar, and the crowd killed them both with swords and knives.
The variety of ethnic, religious and tribal tensions that could flare up makes governing Iraq so difficult that many leaders in the surrounding region and beyond accepted the presence of a brutal regime as necessary to hold the country together.
No outside power intervened after Hussein's use of poison gas to quell a Kurdish uprising in 1988, nor when he used attack helicopters to kill tens of thousands of Kurds and Shiites who rose up against his regime after the 1991 gulf war. Nor was there a strong outside reaction later in the 1990s, when Hussein drained the marshes that provided the habitat and livelihood for generations of "marsh Arabs" in southern Iraq, who were hostile to the regime. The full extent of Iraqis' suffering is only now becoming known as torture victims and others feel free to talk for the first time.
The coming months will test whether the United States and Britain, as occupying powers, can hold the country together with a lighter touch, persuading Iraqis to suppress ethnic tensions in pursuit of a freer society.
President Bush wants to do more than just stabilize Iraq. At a press conference March 6, he voiced confidence that Iraq would serve as an example to the region. "The Iraqi people are plenty capable of governing themselves. Iraq's a sophisticated society. Iraq's got money. Iraq will provide a place where people can see that the Shia and the Sunni and the Kurds can get along in a federation. Iraq will serve as a catalyst for change - positive change," he said.
"I'm not dismissive of democracy ... but it's going to be very, very difficult to achieve," she said. "You have to get political representatives to agree on power-sharing. Then you have to get people whom the leaders represent to buy into the deal.
"And then there is a deeper level: Is it possible to have a multi-ethnic Iraqi nation where Sunnis are not controlling the levers of power?" she said.
Pollack said a "cleverly designed federal system" will be required. Kurdish leaders in the north have made a step in this direction by agreeing not to work to change Iraq's borders, provided Kurds retain the autonomy they have enjoyed for the past decade under the protection of U.S. and British warplanes patrolling the no-fly zone in northern Iraq.
Pollack also praised the Bush administration for quickly agreeing yesterday to the presence of Turkish observers in Kirkuk to ease Ankara's fears of an independent Kurdistan.
But Turkey won't be the only neighbor watching anxiously as events unfold in Iraq. Shiite-ruled Iran might be tempted to meddle on behalf of Iraqi Shiites if they feel they're not getting a fair share of power. Autocratic, Sunni-dominated Saudi Arabia has two fears, Hawthorne said: a rough-and-tumble Iraqi democracy and an ascendant Shiite majority - both right next door.