As a red sun dropped to the desert horizon, children shouted and splashed in the waters of the Euphrates River and their families picnicked at tables in the shallows.

Carefree evenings have returned for many in Syria, but for the people of Deir al-Zour, a desert city in the east near the border with Iraq, the peace is still awaited.

“Deir al-Zour gave a lot of people and a lot of blood,” said Ali Muhammad al-Hilou, 45, who lives beside the ruined Othman bin Affan mosque, where some of the first protests began against the former dictator Bashar al-Assad in the 2011 uprising. “The government should look after Deir al-Zour more.”

This city, the surrounding province, and its people, veer between pride for being among the first to stand up to the Assad regime and resentment at the neglect shown by its successor, the government now led by the rebel leader turned president, Ahmed al-Shara.

Deir al-Zour has the sad notoriety of being the most heavily damaged city in all the country, according to United Nations Habitat, the urban development organization. It was battered through years of shelling and bombing by the regime in a 13-year civil war against it opponents and later, the terror group Islamic State, or ISIS.

Block after block, bombed to ruins, has been left uninhabitable, including 75 percent of all housing in the city, according to the United Nations Habitat.

The Euphrates River, a fount of life and civilization since ancient Mesopotamia, became a front line and remains so today. Its famous suspension bridge is downed and marks the limit of Syrian government control.

Forces loyal to the new Syrian government control the city and main highways on the western bank of the Euphrates.

Across the river is an American-backed, Kurdish-led militia known as the Syrian Democratic Forces, or S.D.F. For years, it has been Washington’s main ally in the fight against ISIS and it still controls much of northeastern Syria.

The rebels who ousted Mr. al-Assad last December, and now form the backbone of the government’s security forces, at times fought against the S.D.F., on opposite sides of the civil war. The new government’s military and the Kurdish-led forces still occasionally clash and remain at odds politically.

The United States helped broker an agreement in March between the new government and Mazloum Abdi, the S.D.F. leader, for him to integrate his fighters into the Syrian Army. But there has been little progress in putting the deal in place.

The governor of Deir al-Zour, Ghassan al-Sayed Ahmed, fretted in an interview about how the division of the province hampers efforts to stabilize the region and resurrect the economy, not least because most of the area’s oil resources lie east of the river in the area controlled by the Kurdish-led force.

“We want the agreement with the S.D.F. to work,” the governor said in an interview. “It is impossible to live in a divided province.”

The governor’s office, a large stone-clad building ringed by iron fencing, stands in the western part of the city that was controlled by the Assad government during the civil war and remains intact.

Driving in across the desert from the west, the city at first appears prosperous, with a large university campus, palm lined avenues, and imposing government buildings. Not far beyond unfold districts of smashed high-rise buildings, mounds of rubble tumbling into the roads and dust-coated streets.

“At night, it is completely dark. It is very scary,” said Kadri Musalli, a storekeeper on one of the city’s main avenues who sleeps in his grocery store to fend off thieves. “This street used to be crazy with people from morning till 2 a.m., and now the only shop here is mine.”

Amid the ruins, families have found a way to live, patching up a room or two, hanging tents over open roofs, or camping on beds on the street.

But life is precarious.

An estimated 88 percent of the province’s population is impoverished, the governor said. Many of the displaced have returned home in recent months only to find their houses damaged beyond repair. Many more are staying away because there is nowhere to live, he added.

“Why did they destroy it so completely? said Velid Yusuf Ahmed, manager for security and access for the Syrian charity, Bahar. “They did not want people to return.”

For some, the community they knew is gone. Only a handful of Christians are left of the thriving community that existed before the war. Five ruined churches in the old Christian quarter in the center of town are a reminder of the diversity of Syria’s cultural heritage.

One is a memorial church to the Armenian genocide, which became a place of pilgrimage for Armenians worldwide.

The people of Deir al-Zour, known for their hospitality, gave shelter to Armenian refugees fleeing the 1915 genocide in the Ottoman Empire, an example of religious and ethnic tolerance, said Hind Kabawat, the Syrian minister of social affairs and labor.

But the brutality of the Assad dictatorship unleashed a terrible bloodletting. The Armenian church was shelled by regime forces and looted.

The Church of Christ the King, founded by monks of a Capuchin Order, was blown up by ISIS fighters who dug a tunnel under the compound to attack the Assad troops who were camped there, members of the local community and officials said.

The city clung to life with no electricity for three years as ISIS closed a vice around it. Supplies could only come in by air on Syrian military flights and families sold their vehicles and homes to pay for a flight out, said Mahmoud Abu Alkhair, 25, a law student who also works as a barista. From the age of 12, he lived through the years of fighting, never leaving the city.

“We feel fear all the time,” he said. “There is no future. I am 25 and my life is at zero.”

Yet there is determination and resilience among the people of Deir al-Zour, and despite their poverty, expressions of hospitality.

“Don’t look at the destruction,” Mr. al-Hilou said gesturing at the ruins of his neighborhood. “This is my home. We will be fine.”

Under the shade of a tree beside the road, Lubna Yassin Shkeimi, a 33-year-old divorcee, was selling instant coffee and cigarettes to earn money for bread.

Internally displaced for 13 years, she said she had come back with her parents and brother four months earlier, and they were living with relatives because they could not afford to repair their own home.

But it was better to be in her home city, she said, as they had suffered discrimination when they were displaced.

“A human being cannot live away from home,” she said.

A welder and former fighter, Moath al-Kurdi, 44, said he had put aside his gun and opened a small shop.

“If we can clear the rubble and fix the infrastructure, then we can do the rest ourselves,” he said. “We just need electricity and water and then we will rebuild.”