THE map of the modern Middle East, a political and economic pivot in the international order, is in tatters. Syria’s ruinous war is the turning point. But the centrifugal forces of rival beliefs, tribes and ethnicities — empowered by unintended consequences of the Arab Spring — are also pulling apart a region defined by European colonial powers a century ago and defended by Arab autocrats ever since.

A different map would be a strategic game changer for just about everybody, potentially reconfiguring alliances, security challenges, trade and energy flows for much of the world, too.

Syria’s prime location and muscle make it the strategic center of the Middle East. But it is a complex country, rich in religious and ethnic variety, and therefore fragile. After independence, Syria reeled from more than a half-dozen coups between 1949 and 1970, when the Assad dynasty seized full control. Now, after 30 months of bloodletting, diversity has turned deadly, killing both people and country. Syria has crumbled into three identifiable regions, each with its own flag and security forces. A different future is taking shape: a narrow statelet along a corridor from the south through Damascus, Homs and Hama to the northern Mediterranean coast controlled by the Assads’ minority Alawite sect. In the north, a small Kurdistan, largely autonomous since mid-2012. The biggest chunk is the Sunni-dominated heartland.

Syria’s unraveling would set precedents for the region, beginning next door. Until now, Iraq resisted falling apart because of foreign pressure, regional fear of going it alone and oil wealth that bought loyalty, at least on paper. But Syria is now sucking Iraq into its maelstrom.

“The battlefields are merging,” the United Nations envoy Martin Kobler told the Security Council in July. “Iraq is the fault line between the Shia and the Sunni world and everything which happens in Syria, of course, has repercussions on the political landscape in Iraq.”

Over time, Iraq’s Sunni minority — notably in western Anbar Province, site of anti-government protests — may feel more commonality with eastern Syria’s Sunni majority. Tribal ties and smuggling span the border. Together, they could form a de facto or formal Sunnistan. Iraq’s south would effectively become Shiitestan, although separation is not likely to be that neat.