CEYLANPINAR, Turkey -- In plain view of the patrons at an outdoor cafe here in this border town, the convoy of gun trucks waving the flag of the Syrian rebels whizzed through the Syrian village of Ras al-Ain. They had not come to fight their primary enemy, the soldiers of Bashar al-Assad's government. They had rushed in to battle the ethnic Kurds.
The confrontation spoke not only to the violence that has enveloped Syria, but also to what awaits if the government falls. The fear -- already materializing in these hills -- is that Syria's ethnic groups will take up arms against one another in a bloody, post-Assad contest for power.
The Kurdish militias in northern Syria had hoped to stay out of the civil war raging in Syria. They were focused on preparing to secure an autonomous enclave for themselves within Syria should the rebels succeed in toppling the government. But slowly, inexorably, they have been dragged into the fighting and now have one goal in mind, their autonomy, which also means the balkanization of the state.
"We want to have a Kurdish nation," said Divly Fadal Ali, 18, who fled the fighting and was recently staying in a local community center here for Kurdish refugees. "We want our own schools, our own hospitals. We want the government to admit our existence. We want recognition of our Kurdish identity."
These skirmishes between Kurds and Arabs take on a darker meaning for Syria as the rebels appear each day to gain momentum, and the government appears less and less able to restore control. The rebels have taken over military bases, laid siege to Damascus and forced the shutdown of the airport.
But the rebels are largely Sunni Arabs, and the most effective among them are extremists aligned with Al Qaeda, a prospect that worries not only the West, but the Christians, Shiites, Druze -- and Kurds -- of Syria.
The fighting in Ras al-Ain, which came after a fierce battle between rebel and government forces last month, demonstrated the complexity of a bloody civil war that has already claimed more than 40,000 lives. Like the sectarian battles in Iraq after the American invasion, the recent violence between Arabs and Kurds in Syria indicates the further unraveling of a society whose mix of sects, identities and traditions were held together by the yoke of a dictator.
Analysts fear this combustible environment could presage a bloody ethnic and sectarian conflict that will resonate far beyond Syria's borders, especially if it involves the Kurds. There is concern that Iraq's Kurds, who are already training Syrian Kurds to fight, may jump into the Syria fight to protect their ethnic brethren. That could also pull in Turkey, which fears that an autonomous Kurdish region in Syria would become a haven for Kurdish militants to carry out cross-border attacks in the Kurdish areas in southeastern Turkey.
"The fear that an Arab-Kurdish confrontation has been ignited might lead the Kurds to ask for additional security forces to protect their lands," said Maria Fantappie, Iraq analyst at the International Crisis Group, who is helping to prepare a report on the Syrian Kurds.
She said that the Syrian Kurdish fighters being trained in northern Iraq were on standby and could be sent to Syria, which would escalate the situation.
Before the uprising in Syria, the Kurds in Ras al-Ain lived peacefully with their Arab neighbors, they say. But the war has shredded those old bonds just as surely as the revolutions in the region have prompted the Kurds to dream of an independent nation uniting the Kurds in Syria, Iraq, Turkey and Iran, and put their own stamp on the great contest for power under way in the Middle East.
"Our time has come after so much suffering and persecution," said Barham Salih, the former prime minister of Iraq's regional Kurdish government. "The 20th century was cruel to the Kurds. Our rights, identity and culture were brutally suppressed."
Amid the fog of war here, there are recriminations. The rebels say the Kurds are cooperating with the government, a common perception among Arabs in Syria. This is partly because the government has withdrawn from Kurdish areas to concentrate on fighting rebel forces, and partly because the Assad government granted new rights like citizenship to the Kurds after the uprising began and issued them official identification cards, which they had long been denied.
At the same time, a powerful Syrian Kurdish militia, the Democratic Union Party, or P.Y.D., is an offshoot of the Kurdish militant group in Turkey known as the Kurdistan Worker's Party, or P.K.K., which has fought an insurgency within Turkey for nearly 30 years. As Turkey has supported the rebels within Syria, the perception has arisen that Mr. Assad's government and the P.Y.D., which is viewed suspiciously by other Kurdish factions, have coordinated to face a common enemy in Turkey.
The Kurds say the rebel fighters that came to Ras al-Ain, some of whom they say belonged to an extremist Islamist group, burned and looted their village, inciting a sense among Kurds that if they did not fight now they could be left out of the spoils of power and autonomy in a post-Assad Syria.
A rebel fighter inside the village, who gave his name as Abu Mohammed, said that some Kurdish militants were fighting on the side of the government, but that rebels had no plans to penetrate deeper into Kurdish territory. "The regime is hoping and working hard to spark an Arab-Kurdish conflict," he said, a black radio in his hand and a sniper rifle slung from his shoulder. "We should save our efforts to fight the Assad forces, not our Kurdish brothers."
A Kurdish fighter worried that the fighting was just the beginning of a long struggle that would outlast the Assad government. "I am sure that Arabs and Kurds will fight each other for years and years after the Assad regime is finished," said the fighter, Abu Zaradashit.
Lying in a hospital bed here, a rebel fighter named Haqer Hammed said he was shot in the leg after being ambushed by a group of Kurdish fighters. "The Kurds want their own small nation," he said. "Arabs don't mind if they have their own nation, but since they are working hand-in-hand with the regime, there will be fighting."
Ceylanpinar, a town of wheat and pistachio farmers and cattle breeders, like its sister village across the border, has a sizable Kurdish population, and the clashes have also heightened tensions here because local Kurds regard the Turkish government's support of the Syrian rebels as a threat.
"Of course we are concerned," said Ismail Arslan, the mayor. Mr. Arslan, a Kurd, explained, "There is clear support by the Turkish government for the Arabs, the Free Syrian Army."
As the mayor spoke recently, a rumor was spreading through town that fighting would resume across the border in a couple of hours. The mayor's assistant received a call from a source who told him that a cease-fire for funerals would soon expire, and that the fighting would start again at precisely 3:30 p.m.
Sure enough, before a clutch of curious townspeople who had gathered at the cafe to watch, the gun trucks appeared at the appointed hour and the fight resumed. Under dimming skies, the playful shrieks of schoolchildren on one side of the border competed to be heard above the din of explosions and gunfire on the other.
Sebnem Arsu contributed reporting from Ceylanpinar, and an employee of The New York Times contributed reporting from Ras al-Ain, Syria.
This article originally appeared in The New York Times.