It is the cradle of civilization -- home of the world's earliest agriculture, its earliest cities and its earliest writing. Abraham lived there, as did Hammurabi and Nebuchadnezzar. Imam Ali, the founder of Shiite Islam, died there.

Empires have many times fought over the region now known as Iraq, and to the victor have always gone the spoils. But today, with a U.S. invasion seemingly imminent, scholars are worried that a 21st-century war may threaten Iraq's antiquities as never before.

Bombing, rockets, artillery and gunfire pose dangers to Iraq's monuments, the scholars say, but the U.S. armed forces have a strong track record in avoiding cultural heritage sites when the actual fighting takes place.

The gravest danger comes afterward, when authority disappears and desperate people cope with chaos by stealing the marketable treasures that reside in museums or in the ground. It happened after the Persian Gulf War in 1991, and Iraq never recovered from the experience.

"We're afraid the whole cycle will repeat itself," said University of Buffalo classicist Samuel M. Paley. "If we do go to war, something has to be done to put the heritage infrastructure back together."

In January, the Archaeological Institute of America issued a statement calling on "all governments" to protect cultural sites both during and after a war, and late in the month a mix of scholars, museum representatives, collectors and dealers made the same case during a briefing at the Department of Defense.

"I did a lot of the talking," said McGuire Gibson, an Iraq specialist at the University of Chicago's Oriental Institute. "They had a list of 150 sites, and I said there were many more than that, and that the biggest problem was the aftermath." The delegation urged defense officials to keep curators and security officials in place, "keep them functioning and bring them back up to full strength," Gibson said.

Whoever is in place after a war will have plenty to do.

Iraq is the land of Mesopotamia, between the Tigris and Euphrates rivers, where Neolithic peoples around 9,000 years ago domesticated animals and developed agriculture, enabling them to form the world's first cities.

Around 3500 B.C., the Sumerians became the world's first great civilization. Cuneiform writing on clay tablets was developed about 3200 B.C. Empires rose and fell in ancient Mesopotamia, from the Akkadians to the Babylonians, Assyrians, Chaldeans, Parthians and Romans.

Abraham, the patriarch of the Torah and the Old Testament, came from the southern Mesopotamian city of Ur, and Hammurabi, the lawgiver, ruled in Babylon, as did Nebuchadnezzar, the conqueror of Jerusalem, and Alexander the Great. Ali died in Kufa in 661 A.D. and was buried in Najaf. Baghdad served as the center of the Abbasid Caliphate for 500 years until it was sacked by the Mongols in 1258 A.D.

Gibson has made a list of about 5,000 archaeological sites from surveys conducted in Iraq, but says there may be 100,000 or more. "The surveys cover only 15 percent of the country," Gibson said, "and anytime we've gone back to a site, we find 10 to 50 additional sites within a 10-kilometer [six-mile] radius. The whole landscape is an archaeological site."

The breadth of Mesopotamian heritage ranges from world-famous tourist attractions like Ur, Babylon, Nineveh, Assur and Nimrud, to tiny, long-forgotten villages in the Iraqi backlands and onetime desert way stations where early Muslim pilgrims stopped on their way to Mecca.

"Baghdad itself is a major medieval site," said Columbia University archaeologist and art historian Zainab Bahrani, who was born in Iraq. "The city is filled with [Islamic-era] buildings from the ninth to the 14th centuries."

During the Gulf War, allied forces bombed inside Baghdad and around archaeological sites throughout Iraq, but inflicted surprisingly little damage. Nearby bombing shook and cracked the fabled Great Arch in the palace of Sapor in Ctesiphon, at 75 feet the widest single-span vault of non-reinforced brickwork in the world.

In Ur, bombs cratered the surroundings of a well-known ziggurat, or tower, and heavy machine guns pocked the ziggurat itself 400 times, Gibson said. A Basra mosque was half-destroyed, he added.

"But bombing in the cities was mostly pinpoint," Gibson said. Iraq's National Museum in downtown Baghdad sits in the middle of a half-dozen military targets, but emerged unscathed except for a few shrapnel scars on the front door when the telecommunications center across the street was destroyed.

In the war's immediate aftermath, however, when the future of Iraqi President Saddam Hussein was in doubt and uprisings spread throughout the country, guards were withdrawn from sites and museums and laws became all but unenforceable. "Nine of the 13 regional museums in both the north and south were raided by mobs who stole things straight from the cases," Gibson said. "At least 3,000 objects disappeared."

Before the war, the Iraqi government had what scholars described as one of the best antiquities infrastructures in the region. But guards were laid off, curators and experts couldn't make a living and emigrated, and a network of watchdogs in rural areas fell apart because inspectors no longer had the money to police local sites and follow up on evidence of looting.

"During the past decade, [there] has been wholesale degradation of sites," said Patty Gerstenblith, a DePaul University heritage law expert and Archaeological Institute advocate. "Part of it is probably the economic boycott [trade sanctions imposed by the allies], and part of it is probably the siphoning off of resources so Iraq can rebuild its military."

As time passed, disorganized looting became more methodical, and Mesopotamian antiquities began flooding international art markets, a phenomenon virtually unknown before the war.

In 1996, dealers were offered nine fragments of what in 1990 had been an intact bas relief sculpture from Sennacherib's Palace in the Assyrian city of Nineveh.

"This must not happen again," said Gerstenblith. "We feel that if the United States is in control at the end of the war, then what happens after the war is controllable. If there is a failure, it will be because people don't want to do it, or didn't think of it. We're trying to take care of the second part."

Donny Youkhanna of Baghdad's Iraq Museum shows remnants of an Assyrian sculpture that thieves had cut in 1996.