Ain Issa, Syria // At a dusty checkpoint on the front line facing ISIL in northern Syria, a steady trickle of cars, vans and trucks passes by on their way from Raqqa, the extremist group’s main stronghold.

The checkpoint near the town of Ain Issa is no more than an abandoned building beside a dirt track, shielded by a waist-high berm piled up along the entire front and held by a group of poorly armed and disorganised Arab fighters in loose alliance with the Kurds who control north-eastern Syria.

As a truck laden with household items emerges from the hazy no man’s land, one of the fighters climbs onto the berm and fires a warning shot into the sandy ground ahead. Another jumps onto a motorbike and careers towards the truck to check the driver’s paperwork before he is allowed to pass.

A little later, a van pulls up, laden with civilians. Inside, 65 year-old Obeid Al Assi, an Arab from a village near Kurdish-controlled Tel Abyad, is returning from a doctor’s appointment in Raqqa, where he has paid 3,000 Syrian pounds (Dh60) to have his heart checked.

“There are not enough hospitals in Tel Abyad,” he says with a shrug, referring to the Syrian town on the Turkish border that was taken by Kurdish forces in July.

Hamad Dijaz, the father of a four-month-old girl, agrees. He took his daughter to Raqqa when she fell ill, he says, boarding one of the shuttle busses that ferries people to and from the city serving as ISIL’s headquarters. His wife has accompanied him, and sits quietly in the van wearing a long black abaya, though she has removed her veil, part of the required dress code for women in ISIL territory.

“In the Kobani and Tel Abyad countryside, most of the people go to the doctor in Raqqa,” said Abu Hamed Ansari, the leader of the motley group manning the checkpoint. A permission from his brigade commander is required to make the journey for civilians to travel to Raqqa, while the front can also be crossed at another checkpoint further down the line, he says.

The van rumbles on, soon to be followed by more vehicles, driving alone or in small convoys. The fighters lose interest in their guard duty, and most vehicles pass through without even a perfunctory security check. Occasionally, Mr Ansari waves at a driver he recognises.

When the Kurds took Tel Abyad, they deprived ISIL of a vital supply line to Turkey. But in turn, the autonomous region suffers from an economic blockade imposed by Turkey.

Ankara is against self-rule in Rojava, as the predominantly Kurdish territory in Syria’s north-east is known, fearing it would galvanise its own Kurdish minority towards secession. It is also mistrustful of the Democratic Union Party (PYD) that rules Rojava and has close ties with the Kurdistan Workers Party (PKK), who resumed their decades-old insurgency against the Turkish state after a ceasefire fell apart earlier this year.

The flow of people and goods across the desert front is known to the administration in Rojava, which tries to keep tabs on who is coming in and out.

“We have some checkpoints for people who travel to Raqqa and we record the names of the people going and coming back,” says Bozan Khali, interior minister of the Kobani canton, one of the three administrative districts that make up Rojava.

Mr Khali acknowledges that these efforts are insufficient. “There are many ways to go to Raqqa, too many ways to try and control.”

Encumbered by the blockade and the widespread destruction caused by the fierce conflict with ISIL, Rojava’s economy is struggling, and the infrastructure is on its knees. Four years of civil war has prompted many to leave the region, a drain on qualified staff.

In contrast, ISIL-held Raqqa is relatively prosperous. The terror group has been able to generate income from a range of activities, including oil smuggling and the illegal sale of antiquities, while the territory under its control has not been ravaged by fighting, although the city is the targetof occasional airstrikes.

As a result, its economy generates a surplus of goods and services that are finding takers among Rojava’s inhabitants.

Foodstuffs like meat, vegetables rice find their way across the front, says Mr Ansari, as he produces cans of energy drinks he has pilfered from a passing truck.

“Everything in Tel Abyad comes from Raqqa but the bread,” says the militiaman, who has been stationed at the checkpoint since the Kurdish advance came to a halt at Ain Issa in July, a mere 50 kilometres from the ISIL capital.

Government officials say that by allowing civilians to travel to and from Raqqa, they set themselves apart from ISIL, which maintains a brutal grip on the people living in its territory, and who hemmed in Kobani’s population during its bloody siege of the city last year.

“We don’t ask them for why they are travelling to Raqqa. Some people have relatives there, some people go there for work, some people go for medical reasons. Some have cattle and sheep there. We don’t want to behave like [ISIL] when we were besieged here,” says Kobani’s defence minister Ismet Sheikh Hassan.

Some of the people heading into the ISIL territory are seasonal workers who went to Turkey for the harvest, he adds.

Kurdish commanders at Ain Issa say that many people crossing the front line into Kurdish territory are refugees seeking safety ahead of the impending offensive to liberate Raqqa or the fighting elsewhere.

“We have no choice but to host these civilians, Raqqa isn’t safe for them anymore. A lot of people are coming in from Raqqa and other Syrian cities,” says Rojda, a commander of a Women’s Defense Unit (YPJ), the female armed wing of the PYD.

Rojava’s porous borders aggravates an already precarious security situation. In June, ISIL launched a second attack on Kobani, this time infiltrating the city with detachments disguised as Kurdish troops.

The attack claimed at least 220 civilian lives, and led to an even denser security network in the canton, where checkpoints have sprung up at virtually every village and where local self defence groups diligently check every car for permissions, arms and explosives. Such scrutiny is not applied to the traffic passing through the front lines at Raqqa, however.

foreign.desk@thenational.ae